The FUEL PRESSURE and the FUEL FLOW (Fuel Volume) is flowing through the bottom half back to the fuel tank. This means fuel flow establishment. A specially drilled hole which goes from the side of the bottom cavity to the top of the centre pin, and from there to the warm up regulator, eases the flow while the engine is cold. This allows to lift the pin higher as the counter pressure is not so high as yet. This makes the engine run richer while it is in the warm up stage. If the engine is warm, the warm up regulator restricts the return flow to the tank and thereby increases counter pressure to the metering pin. The air sensor plate has now restriction against the applied pressure to lift. This now makes the engine run lean. Now back to the fuel distributor: By moving the fuel metering pin up, this allows the fuel to flow from the bottom cavities to the top cavities. As the top cavities do not have a pressure relief valve, this makes to bend the thin steel plate downwards, and the fuel can then enter in to the injector discharge hoses.
Shortcut back K-Jetronic site plan.

THE WARM UP REGULATOR is a small aluminium casting, mainly located near the engine block, the hottest spot in the engine environment. There are four different types of warm up regulator. The first one is just a thermally heated regulator which rellies only on engine heat and is mounted on the engine block. The second one has a heating element internally which is operational via a cable connector and connection from the ignition. The third type is the same as the second one, but has in addition also a vacuum hose connection to the regulator to keep more counter pressure to the centre metering pin if there is no vacuum if the engine is on full load. This stops the backfiring into the manifold by sudden acceleration. The fourth version is the latest which is magnetically controlled via the oxygen sensor and temperature coolant sensor. This warm up regulator is not as such like the others, but is changing the counter pressure via the computer due to the engine load factor, rpm factor, timing factor, oxygen sensor results, and throttle body position. This unit is no longer fitted onto the engine block but, instead, onto the fuel distributor itself. Due to this very complex and bulky unit a special pressure regulator has been fitted into the fuel line near the fire wall. Cars which have this system, I think you would not be able to afford these, as the price tag is way over the $100,000 mark. What's the warm up regulator's job? Please see in Fuel Distributor section for explanation. Can a warm up regulator be fixed? YES, only if you have the right tool from INTER-JECT, the LB-291/2F, otherwise NO. Buy a new one and get into trouble calibrating the new one to the worn engine, and still you have not the tool to do so. The warm up regulator is the kidney of the whole system which makes the engine run properly when it is cold. However, if the engine runs lumpy when it is cold, you know and I know, the warm up regulator is out of calibration to the worn engine and needs re-calibrating with our flow meters.
Shortcut back K-Jetronic site plan.

THE SYSTEM PRESSURE REGULATOR, as described in FUEL DISTRIBUTOR is just as important as the warm up regulator. The only difference is the system regulator opens up at a pressure of 500 KPA or 5 BAR, if the pump delivers 8-9 BAR this means we have 3-4 Bar over pressure, and of course flow with it. The system regulator discharges at this point only 2 Bar. If we could measure it correctly with the INTER-JECT FLOW METER AND PRESSURE GAUGE which in terms flow back to the fuel tank. What happens to the rest of the pressure and flow? Oh no, the engine is not running! We still have to account for 1 to 2 Bar pressure and flow. Yes, it is the counter pressure which flows through the warm up regulator. So 2 Bar is flowing through this regulator with a flow of say 20 l/h and if the engine warms up we will have 3 bar counter pressure towards the metering pin, and a flow of only 10 l/h towards the fuel tank, where by the system pressure discharge increases, not in pressure, but in flow only. The set system pressure is 5 bar. Set is set! Just what has changed is the flow. Go on, measure it with your flow meter, if you have one, and see how cleverly this system works. The location of the system pressure regulator is in the fuel distributor, somewhere on the side. On some models it may be fitted on the top half of the casting, or on other models on the bottom half of the casting.
Shortcut back K-Jetronic site plan.

As we know, there is a need for all mechanical workshops to have the right diagnostic and servicing tools to cope with the new technology. More so, if we look at a newly printed article from the Service Station Magazine, in the September 1992 issue. They still insist on using a gradient test beaker for a fuel volume test! To do so, the hose from the end of the system pressure regulator must be disconnected and with a new piece of hose extended and used for the volume test. Try to do this on K-JETRONIC or any EFI car. Firstly, you do not know all the different volume readings which are correct on different car types and models. Secondly, any flow discharged after the pressure regulator will have an extreme amount of aeration (air bubbles) and still you have no way to check a flow between the metering pin and warm up regulator, as you can not put the hose in open air. This must be a closed loop to be satisfactorily tested, otherwise the engine will not run, as there is a total pressure loss. Do not forget that the warm up regulator only bypasses limited fuel FLOW back to the fuel tank which can be only measured with the INTER-JECT flow meters, as they are connected into a closed loop. INTER-JECT flow meters are colour coded to give the mechanics the exact flow requirements of most types of vehicles. The general fuel flow must be in the 100 l/h range or higher which is colour coded "green". Any medium blocked fuel filter can reduce the fuel flow into the 80 l/h range, which is colour coded "yellow". Faulty fuel pump or severely blocked fuel filters can restrict the flow to 60 l/h or below, which is colour coded "red". This means at this point that there is an indication of a severe fault. This colour coding on glass flow tubes is on system flow tubing. The colour coding on injector flow tubes is "red" at 15 cm3/min which means the injector flow is too rich on idle. The other colour coding is "green" at 10 cm3/min which is the drop point of the indicator to be in the lean area of any four cylinder car.
Shortcut back K-Jetronic site plan.

Please remember that K-JETRONIC systems are only fitted into very expensive cars which have a very high price tag. Just to mention some models; VOLVO, MERCEDES, AUDI, SAAB, BMW, PORSCHE. Just to damage some or only one component may cost you, or if you talk your way out of a paper bag to the customer, he or she may be up for big $$. So rule No 1 is, if you do not know anything about K-JETRONIC leave it as it is, or redirect this job to someone else who has the know how and the testing and servicing tools. As there are different types of K-JETRONIC on the market, which ranges from K-JETRONIC I, II, III, IV, V. The latest model is K-JETRONIC (5) which is installed in MERCEDES BENZ and PORSCHE with OXYGEN SENSORS. The overall principle is still the same, except the counter pressure is controlled by an electro magnetically field, or to explain better, pulse duration's which change counter pressure in the fuel distributor for the oxygen sensor requirements as well as other sensing components. The warm up regulator is no longer installed in this type and is taken care of, from the magnetically correction unit which is fitted on the side of the fuel distributor. This unit receives continuous (HF) HIGH FREQUENCY correction impulses from the control unit, known to us as the " COMPUTER ". The COMPUTER receives correction current flow from those semi components like oxygen sensors, coolant sensor, and many more, to stabilise the best and correct counter pressure to the fuel metering pin. All this may sound to you like UNIVERSITY stuff, yes it is now going that way and only YOU will share prosperity in your business. Think about the challenge in front of you, to be able to repair K-JETRONIC 5, is now open for you. But before you do.... make yourself familiar with the older stuff which is in the past. Think what will happen to all the other mechanics? They will never be able to understand 20% of my write up and it may be for them, that the technology will just overtake their knowledge to an un-recoverable stage. The result is " go out of business ".

ANY ENGINE WHICH IS FITTED WITH K-JETRONIC will develop at any stage a poor idle while the engine is cold. You now know where the problem is. There may be the problem of restricted flow from the fuel warm up regulator, which may develop restricted flow due to dirt or is out of calibration due to the worn engine (compression loss). But do not be too sure before you jump horses. First to basic, and I do not have to repeat myself over again. The best and quickest confirmation to yourself and to your customer is as follows; remove the air bellow (HOSE) or air filter on the top of the air sensor box. Start the engine and press the sensor plate gently downwards. Can you feel the counter pressure against the sensor plate? Just press it a bit more and see the engine become very smooth in idle. Now I ask you what is wrong?? You still point your finger at the WARM UP REGULATOR. I tell you, you are wrong in one way, as you have not done 3 simple checks.
They are:
1. Check compression on each cylinder, this may lead to the loss of air flow via sensor plate which can not be lifted or pressed down far enough.

And this is probably the simplest check: Check the bellows next to the throttle body, particularly in the area where the piping that leads to the Auxiliary Air Valve, the bellows on the fuel distributor, and other intake air piping for cracks as any air leaks will cause a lean condition resulting from un-metered air entering the manifold. These can be adjusted out, but if they are discovered later, could cause a dangerous condition (backfiring, etc) if the system is not re-adjusted. I've learned this from both a 1978 VW Scirocco (K-Jetronic) and a 1981 VW Scirocco (KE-Jetronic O2 sensor equipped). $400.00 (U.S.) for parts / troubleshooting by a mechanic (on the '78), and it was solved with less than $100 by myself when he couldn't figure it out. (Above paragraph has been sent in by Mr. Kirk McGehee)

2. Check if the fuel pump has been recently changed with the right type and same brand, you can     see if it is new on the housing.
3. Check with the right tools now the fuel FLOW and PRESSURE on the fuel pump. Check the system FLOW and PRESSURE as well and the resting pressure. Connect the servicing unit between the warm up regulator and fuel distributor for correct regulator operation pressure and flow changes. The last thing you may not be able to do, re-calibrate the warm up regulator to a lower counter pressure, as a special training and bench work is involved, and you must register yourself for a K-JETRONIC repair course with our training manager Leo Karnauchow in INTER-JECT Office Ballina NSW.     
**All information are partly NOW in the Members Data Pool as refresher! **
Shortcut back K-Jetronic site plan.

THE ENGINE WILL RUN SMOOTHLY, after it has been warmed up. This is a sign of warm up regulator fault.
1. Out of calibration to the RICH side (too far open) must be reset by trained personnel only.
2. Out of calibration to the worn engine (higher counter pressure against the metering pin). This     causes the cold engine to run very lean. A new warm up regulator will only do very little as the     sensor plate still has not enough air flow to be lifted high enough.
3. Warm up regulator restricted with dirt or blocked or faulty in the electrical circuit. Remove the     hose from the regulator towards the fuel tank and check for fuel flow. Use test light or ohm meter     for continuity check in the heater wiring circuit or plug.
**All information are partly NOW in the Members Data Pool as refresher! **
Shortcut back K-Jetronic site plan.

A BACKFIRING FROM THE INLET MANIFOLD, towards the air sensor plate, can have a devastating result of damage to the air sensor plate arm. There is, in the air accumulator, a rubber stop which may give way if heavy return pressure force is against it. This can then interfere with the previously set mixture setting. The engine may then run very lumpy or not at all. The reason for backfiring in the first instance is too lean a fuel mixture on acceleration, plus a very high counter pressure to the fuel metering pin. Car manufacturers have prevented this from happening by using an updated warm up regulator with a vacuum adaptor. This will now in terms change the main principles, regardless if the engine is warm or cold. The centre counter pressure will only then increase in loss of vacuum, which lets the tension spring go free to be able to restrict the outlet flow of the warm up regulator to increase the counter pressure. If the engine is on idle, there is high vacuum to the diaphragm in the warm up regulator and the tension spring has been pulled back to increase the flow and drop the counter pressure. Vacuum assisted warm up regulators take the flat spot, backfiring and hesitation away from any modern car. This makes the airflow in the manifold lift the sensor plate higher to make the car run richer while on idle. Leaner, as more air flow passes the gap of the sensor plate, which lifts the sensor plate higher, but at the same time the counter pressure starts to build up to work against the metering pin which adjusts the fuel mixture to a leaner setting. The vacuum assisted warm up regulator is now compensating for more counter pressure as the vacuum loss gradually increases.
Shortcut back K-Jetronic site plan.

RPM LOSS ON HIGH SPEED is usually fuel related. This can be simply found with the INTER-JECT LB-291/F or 2F. First check the main fuel flow, which must be between 120 to 140 l/h with a system pressure of 5 bar (checking point is fuel distributor and fuel inlet line). If the fuel flow is only 40 or 80 l/h, change the fuel filter and check again. If there are no changes after the fuel filter has been replaced, remove the lift pump and check the fuel-sock for any softness or if it has been sucked in together, which restricts the fuel flow. This causes the pressure pump to be extremely noisy as it works in a vacuum suction situation. A spring will keep the sock apart for a larger area to suck more fuel through. Check fuel lift pump for flow only and also the main pump for flow and pressure. Most important, make sure the fuel tank is at least 1/4 full, as the fuel rushes to one side of the fuel tank when you are cornering the vehicle. This makes the pump only suck air and the engine will lose rpm. Check the fuel tank for WATER, and water in the fuel distributor as well. Water can be only removed with the INTER-JECT LB-288/4 as this unit will run the engine on its own with the fuel tank disconnected. Or now the LB 291/2F equipment with the original car fuel pump in action where chemically, the water will be removed with INTER-JECTRON. (INTER-JECT'S own designed and developed chemical with colour fault indicators).
Shortcut back K-Jetronic site plan.

PRESSURE SETTING, while the engine is running must be 500 kpa or 5 bar. However, if the fuel pump has been changed with a different type than the original has been, the pressure could be higher or lower as it depend on the fuel flow. Still, whatever it may be, fuel flow or pressure, the setting must be 5 bar. Remember, low fuel flow makes a very slow pressure recovery. High fuel flow makes a very quick pressure recovery with no pressure loss, as the fuel pump flow is still higher than the system pressure setting. So, if you have fuel flow of 140 l/h, this makes a very quick pressure build up which may be 5.2 bar. Because of this higher fuel flow, we call this pressure ACCUMULATION. There is no time for pressure to settle as the high fuel flow overrides and queues up higher pressure before the pressure release valve. On the other hand if we have only 120 l/h fuel flow, the pressure in the system would be exactly 5 bar. If you would adjust the system pressure which has a reading of 5.2 bar by a flow of 140 l/h to exactly 5 bar, so your flow would increase from 140 l/h to 152 l/h and this is exactly the right result. SO, the LOWER THE PRESSURE the flow increases. So the higher the pressure, FLOW DECREASES. [Explanation] So your system pressure is set exactly to 5 bar when the engine is 'COLD'. Some fuel flow and pressure is also flowing via the warm up regulator. Why does this warm up regulator flow and pressure not show up in the system pressure setting difference will be a slight increase in the fuel FLOW as the engine becomes 'WARM OR HOT'. The fuel flow increase is only 2 - 3 l/h which is not significant to change the system pressure to a higher reading. Therefore, you and I know that the right type of " FLOW METERS AND PRESSURE GAUGES " are essential for K-JETRONIC and E.F.I. vehicles. It is required to connect the service flow meter and pressure gauge between the fuel distributor and fuel supply hose to check for SYSTEM FLOW and SYSTEM PRESSURE. No fuel leaks are permissible on connecting points. Next, if you suspect a faulty warm up regulator, or the possibility that it is out of calibration, which most of them are. Connect the service FLOW METER and PRESSURE GAUGE only when the vehicle is cold, between the ' CENTRE FUEL DISTRIBUTOR OUTLET ' and the ' WARM UP REGULATOR INLET '. This allows you to measure the correct warm up FLOW and increasing  C o u n t e r  P r e s s u r e  as well as decreasing flow, while the engine is running. If you connect the service unit between the fuel distributor and return line, the fuel pressure will be very low. The narrow size of the fuel line causes fuel ACCUMULATION or PIPE FRICTION that the pressure gauge reads some pressure. On the other hand the fuel flow would be just above 10 l/h higher, as we have the warm up regulator flow joining into the same return line. If you disconnect the center counter pressure hose from the fuel distributor, the result is total loss of system pressure, holding pressure and accumulator pressure. In other words, the car won't start.
Shortcut back K-Jetronic site plan.

THE MOMENT YOU switch the engine off while the FLOW and PRESSURE GAUGE is connected in series between the fuel distributor and fuel pump pressure side, the gauge will drop to a resting point. In most cases it is a reading above 200 kpa or 2 bar. Never less! This is caused as the system regulator valve shuts approximately at 4.2 Bar. However, a bleed off of fuel via the warm up regulator will bring the resting pressure to 3 Bar or a minimum of 2.2 Bar as the compression spring in the warm up regulator shuts off the inlet piping. This causes resting pressure in the fuel distributor. If p check for a system leak. INJECTORS ARE THE LAST TO BLAME FOR LEAKS, so please remember. Injectors in K-JETRONIC play the role strictly of DEPRESSURISING VALVES, that's all they are !! For total system pressure loss, there are only 2 main items to check.
1. The check valve or one way valve in the fuel pump is faulty.
2. The 'O' ring on the system pressure relief valve is leaking.
Secondary checks:
1. Fuel line is leaking somewhere on joints.
2. The fuel accumulator diaphragm has a small pin hole and is dribbling out from the safety discharge pipe.
Shortcut back K-Jetronic site plan.

THE FUEL ACCUMULATOR, OR BETTER KNOWN IN AUSTRALIA AS FUEL DAMPER, is located just after the fuel pump. So it's location is between the fuel pump and fuel filter. All K-JETRONIC systems must have this very important component fitted into the fuel supply line. The housing of the fuel accumulator is split into two parts, the same as the fuel distributor. The difference is that the top part houses a very heavy compression spring, and as well, it has a safety fuel bleed outlet or, in other words, atmospheric discharge opening. The joining point to the bottom half is a metal folding lip and houses a heavy duty diaphragm. The bottom part has internally a metal fuel deflection plate, where the inlet fuel line is connected to a metric fitting. The fuel outlet is then taken off from any part of the bottom housing, as well from a 14 mm metric fitting. The exact location of the fuel accumulator is as close as possible to the outlet of the fuel pressure pump, or main pump. This will inhibit any fuel pressure noises from the fuel pump. As we have learned, the relationship between fuel flow and fuel pressure, are constantly changing. The fuel accumulator will now assist in keeping the pressure and flow in the fuel distributor bottom half always the same. The fuel accumulator now has the ability to take into itself the reserve pressure and flow from the fuel pump. Due to the long fuel line to the engine bay, known as fuel pipe flow friction and the system pressure regulator valve in the fuel distributor head, this keeps the diaphragm of the fuel accumulator compressed and therefore stores more fuel while the pump is running. By acceleration, some of the fuel FLOW AND PRESSURE will enter the top half of the fuel distributor, which can only go ONE WAY to be discharged by the injectors. The diaphragm in the fuel accumulator can now compensate for the fuel diversion to the injectors, or fuel diversion via the system pressure relief valve. The fuel accumulator also plays the role of controlling the fuel flow ' back up '. Either to the injectors or via the system pressure valve.
Shortcut back K-Jetronic site plan.

K-JETRONIC INJECTORS are, in general, serviceable. You can flush them with a pressure setting of more than 4 bar and as well back-flush the injectors by keeping the pintle open with a special locking tool. To understand K-JETRONIC injectors properly, you must see the purpose; why they're in a motor car and the way the injectors work in a pressure/flow principle. As mentioned before, the injectors are only depressurising valves. No electronics or magnetic coils drive these injectors. Only FLOW and PRESSURE changes drive these precision depressurising valves. For example, the diesel engine injector has a very close similarity to the K-JETRONIC injector. The only difference is the pressure variation. Diesel injector needles are lifted off the seat only by extremely high pressure with very, very low flow. K-JETRONIC injectors are pushed open by medium pressure with variations of flow and pressure. A return spring with medium tension keeps the injector pintles closed to stop fuel dribbling into the manifold. Each injector, depending on the type of engine, has a main seal to stop air leaks into the manifold. Other types have a bakelite (it is a type of very brittle plastic but heat resistant) cone seat and 'O'ring as well, which are bolted onto the manifold (VOLVO). The quickest way to clean K-JETRONIC injectors, is to remove them from the manifold. Use a wire brush, driven by an electric motor, and brush all the carbon from the injectors. Clean the pintle side as well with the wire brush. Soak all injectors in an ORGANIC SOLVENT SOLUTION, the best is INTER-JECT CLEANER, BLUE, or INTER-JECTRON which definitely leaves all other mineral, hydrocarbon oil based injection cleaners on the market, totally as a foolishly invented joke that remain as an end user "rip off". After soaking for 30 minutes, use compressed air, blow through the injector, listening for the distinctive resonating pressure sound. Repeat this 6 times per injector, with a bit of liquid filled each time into the back of the injector. Look for the initial spray pattern at the beginning of each air blast. The filter basket in the injectors can not be removed, however, with a special small tool, the pintle can be locked into an open position and thereby the injector can be, with a different pressure setting, back-flushed to clean the filter basket backwards. Each time the injector has been removed from it's seat, the SEAL or 'O' ring has to be checked for possible hardness or damage, or, if necessary to be replaced. A plastic insert inside the injector, which keeps the small compression spring behind the pintle cone under specific set pressure, may melt and restrict the flow and spray pattern via the offending injector. This happens mainly if the engine has been overheated. (Head gasket leak and coolant loss in the radiator). If this happens, do a flow test into graduated test beakers while all injectors are removed, but still connected onto the fuel lines. If one or more injectors play up in the flow test, swap these injectors with good flowing injectors to the same fuel lines from the fuel distributor. If these become good and the others bad, exchange or repair the fuel distributor as the internal seals have been blown to those injector fuel lines.
Shortcut back K-Jetronic site plan.

K-JETRONIC fuel pumps are certainly different to E.F.I. fuel pumps. Firstly, physically they may be larger, as they have a larger roller/pressure chamber, which still can vary in difference from a 4 cylinder car to a V8 Mercedes Benz car. K-JETRONIC fuel filters are as well larger than E.F.I. filters. The fuel flow of a 4 cylinder Volvo must be in the range of 140 l/h by a system pressure of 500 kpa or 5 bar. To check the fuel flow of the same vehicle, but this time the real flow from the fuel pump without any pressure, would run the flow meter off the scale. The approximate reading would be 250 l/h. Now to connect the fuel pump to a pressure source, like a fuel distributor of 500 kpa or 5 bar, this will slow down the fuel flow just to 140 l/h. So you can see the relationship between flow and pressure. All this can confuse any mechanic at any time and therefore a proper schooling in K-JETRONIC is extremely ESSENTIAL to be able to work confidently on these injection systems. Also, you must sooner or later invest in INTER-JECT flow meters and calibrated pressure gauges, as you can not afford to be without them, and losing on business.
Shortcut back K-Jetronic site plan.

RE-CALIBRATIONS ON WARM UP REGULATORS will be a closed door for you and will remain closed, until you have our exact training on how to do this. This applies also for EFI airflow meters, mapsensors and computers. Special tool possession is essential. If you have these tools the door will be open for you. Please make an appointment for a K-JETRONIC course with Leo Karnauchow in Ballina, Mobile 018 445011. Equipment can be ordered and shipped off direct from INTER-JECT in Ballina, Phone (018) 445011 Or contact you nearest INTER-JECT Distributor.
Shortcut back K-Jetronic site plan.

POLYTHENE HOSES, or metal piping, to and from the fuel distributor, have been fitted in all K-JETRONIC systems. Their main purpose is to prevent hose or fuel line expansion, which may burst the fuel line and would be a fire hazard to the vehicle. The safety requirements are that any fuel supplying line must have a bursting point of at least 30 bar. Metal lines are better for holding pressure, but are disadvantaged in line flexibility. This means that on any MERCEDES BENZ, the fuel injectors are connected to metal lines which are very fragile in bending and awkward when the injectors are removed from the manifold with the lines connected for flow test purposes. There is only one way out, which is keeping a spare set of polythene lines with fittings in the workshop which can be quickly exchanged for test purposes. Polythene hoses are made from a type of hard plastic which is fuel and acid resistant. Some vehicles also have some kind of heat shield over the polythene hoses which may only be a rubber hose sleeve. The injectors can be very easily removed from the manifold while connected to the lines for flow and volume tests. Remember; never cut these hoses anywhere you may decide to connect a pressure and flow meter between them. Rule No 1: always use the fitting connections by un-doing them and join other connections in series for the testing equipment. Also, be aware that, as K-JETRONIC has only been manufactured in Germany, the fittings are in "METRIC", made to DIN specification of thread pitch requirement which should be INTERNATIONALLY known. The common cars which have polythene hoses include BMW, PORSCHE, VOLVO, SAAB and some AUDI models. Metal piping is found in all MERCEDES BENZ models and in some late model AUDI's.
Shortcut back K-Jetronic site plan.

YES, POLYTHENE HOSES can be repaired quite easily. The only thing you need is a special tool you can make yourself, which enables you to clamp the polythene hose into a vice so you can knock in any fitting which has a barb holding it into the hose with a rubber hammer. If the hose has been kinked, it is advisable to change it, as the point of the kink may burst under pressure, and it can restrict the flow which can build up higher pressure to the pump side. If the injector hose between the injector and distributor has a kink, it must be changed, as a flow restriction to the injector may put the engine out of balance. Where can you buy these hoses? In any HYDRAULICS outlet, on rolls, in different sizes. To make the tool which is used for clamping the hose end into the vice, use an aluminium block, say 8 cm long x 5 cm high and 3 - 4 cm thick. Drill through the 3-4 cm thick side a hole which is just a tiny fraction larger than the hose. The hole must be drilled from one side right through to the other side of the aluminium block. Then, with a hacksaw, cut the aluminium block in half, so that you have cut the drilled hole into two halves. The poly hose will then fit exactly between the two halves of the block, in the drilled channel. Let about 10 mm of the poly hose protrude from the aluminium block and clamp the block into a vice. Because of the hacksaw cut, the drilled channel is now the same size as the hose. This keeps the hose very firm in the vise. Then use the required fitting and hit it into the hose with a rubber hammer. Keep this tool, INTER-JECT's own design, for later use.
Picture plan for this tool you find in the Data pool or in your Free Computer Disk update to download inside from the Data pool.
Shortcut back K-Jetronic site plan.

COLD START INJECTORS are also found in some EFI vehicles. Just about every K-JETRONIC system has a cold start injector fitted into the air manifold. These injectors are activated for only approximately 7 to 8 seconds from the starter motor via the thermal time switch (see "THERMAL TIME SWITCH" section for more information). Cold start injectors are electro-magnetical solenoid valves, with a fine fuel spray due to the 5 bar fuel pressure setting from the fuel distributor. There are variations of cold start injectors for all different engine sizes and models. As mentioned before, banjo type fittings are used in conjunction with polythene hoses for safe and leak proof connections. The location of this injector varies in different vehicles. The BMW 3 and 5 series has the cold start injector fitted under the manifold. To get to the injector, the car must be lifted by hoist. Other cars have this injector fitted right in the middle of the manifold. On EFI CARS, like the Toyota Camry or Mazda, this injector is clearly visible. On K-JETRONIC cars, it is the same on the AUDI 5+5, 80, 100, and right throughout the Mercedes Benz model range, except for the 560SE and SL. Press F8 for cold start injector information . . . . . .
Shortcut back K-Jetronic site plan.

The THERMAL TIME SWITCH is a timing device used to control cold start injection to a time limit, to prevent possible engine flatting from excessive fuel. The operation or activation of the thermal time switch is via the starter motor for approximately 7-8 seconds, and secondly, the temperature of the coolant in the engine near the thermostat. The warm or hot coolant stops any activation of the cold start injector until the coolant temperature drops to 25 degrees centigrade. Below this temperature, the starter motor only can activate the injector again 8 seconds. There is only one chance given to you to test the current flow from the thermal time switch. After, you must wait for at least 5 minutes for a new current test. As soon as the contact points are open, the earth from the cold start injector is taken away. The injector stops injecting fuel. By warming up the engine, the coolant temperature keeps the contact points from the thermal time switch open, regardless of whether the starter motor is activated or not. The coolant temperature overrides all previous operations for any possible cold start injector activation while the engine is hot. It happens on many occasions that the contact points or the heating element on the bimetallic strip are melted together or burnt off. This is caused mainly from jump starting. An external battery connected to the faulty internal battery in series instead of parallel, which is 24 volt, will cause this melt down of the thermal time switch. The result is continuous cold start injection each time the starter motor is activated. The engine is flooded with petrol and cannot start. The reason for this is that very thin cable is used in commercially manufactured "JUMPER LEADS" which forces the car owner to connect in series to make the engine turn over. Should, under any circumstances, the oil level in the engine sump be higher than normal (this applies for all vehicles with cold start injectors fitted) check the oil for fuel dilutions. In most cases, each time the thermal time switch comes to a closed point position while the engine is stationary and turned off, it injects the resting or residual pressure into the manifold due to a static current in the computer as the computer may have bad or no earth on most EFI cars. With K-JETRONIC, the 'PLUS' cable from the battery is always under load to the starter motor. Dirty starter solenoid contacts may let pass 4 to 6 volts to the cold start injector and load it up with positive current. The closed contact points in the thermal time switch give an earth circuit, which activates the cold start injector for complete pressure drop from the fuel distributor into the manifold. My advice is to put your fingers onto the cold start injector to feel if it is warm as the engine is cold. Be extremely suspicious even if the injector is only slightly warm. Disconnect the fuel line from the cold start injector and check fuel pressure. Remove the cable from the cold start injector, check for current flow with a digital volt meter.
Shortcut back K-Jetronic site plan.

SO YOU HAVE TOTAL PRESSURE LOSS! The quickest way to find out in which direction the fuel distributor has pressure loss is to disconnect the fuel return line. Use a small container to catch any fuel lost from the system pressure regulator outlet (return line connecting port). Disconnect the return line from the warm up regulator, the joining point from the main return line. See if there is a steady petrol flow. If not, use a small container to catch any fuel loss. Finally, disconnect the cold start injector fuel line after one hour. Check if there is any fuel in the fuel catching containers (return outlet and the return line from the warm up regulator). By disconnecting the pressure line to the cold start injector, if no, or a very small amount, of fuel pressure is noticeable, then change the CHECK VALVE in the fuel pump. Check at the same time for an accumulator leak from the air bleed, and a fuel line leak on any joint. If you have a continuous leak from the return line connection port or any fuel accumulation in the container, then change the seal on the system pressure regulator valve. If you have continuous flow or a dribble from the warm up regulator return line, then change the WARM UP REGULATOR. If you have the INTER-JECT LB-291/F or 2F, open up the regulator and remove the rust spot, dirt or corrosion spot under the counter pressure inlet or outlet side. Use the INTER-JECT tool for a successful on car or off car re-calibration on the warm up regulator. Lastly, if you do not find any fault in any of those items, please refer to the "THERMAL TIME SWITCH" section of this menu . . . . .
Shortcut back K-Jetronic site plan.

THE AUXILARY AIR VALVE, or air slide, is found in every car fitted with a cold start injector. This also applies to EFI cars. This air valve consists of a full aluminium body encasing a bimetallic strip which changes its structure if heated. The heating element is in the centre of the bimetallic strip. The ignition supplies the power to the heating element. The bimetallic strip is connected to a metal disc with a small cut out for the air to pass through. A return spring keeps this metal disc somewhere near the "adjusted" resting point for a bigger opening to let more air pass through when the engine is cold. Hose adaptors on each side of this air valve keeps a very tight seal which prevents an airleak from the throttle body to the manifold. How does this air valve work? It is an improved version of the "CHOKE" we know in carburettor cars. The working principle of this air valve, as the name says, "AUXILARY AIR VALVE", is that it passes more air directly to the manifold when the engine is cold. The air will be drawn in before the throttle body via this valve and directed into the manifold. In other words, more air can by pass the throttle body which lifts/lowers the air sensor plate for enrichment and higher rpm's of the engine, as in EFI cars, where the vane airflow meter or any other sensing device will be moved for more enrichment and higher engine rpm's. The ignition is heating the heating element constantly. The bimetallic strip slowly changes its own structure (TURNS or BENDS) which moves the slotted air passing plate to a lower/slower airflow. Known as "AIR FLOW RESTRICTION", this will gradually slow down the engine rpm and the engine becomes leaner. This is also known to mechanics as "AIRSLIDE" as this is the way this component works. Can this auxiliary air valve go out of calibration? YES, it will become lazy or even inoperative, when the engine encounters piston ring wear. This applies to all EFI or K-JETRONIC vehicles. Test the heating element continuity, and if the circuit is open, change this auxiliary air valve for a new one. If the circuit is closed, you can adjust the slide disc by loosening the yellow painted adjuster screw. Move the slide disc with a screwdriver to a more open position and lock the adjuster screw. Remember, the air auxiliary valve must be cold for correct adjustments. The location of the air auxiliary valve is sometimes in a very inaccessible position, as in Toyota EFI vehicles or BMW's. The Mercedes Benz air auxiliary valve is a completely different type, as it is warmed by the coolant. A mercury type filled insert in the housing expands to change the air by pass to the manifold.
Shortcut back K-Jetronic site plan.

EVERY FUEL INJECTED CAR has some type of check valve (NON RETURN VALVE) fitted externally or internally in the main fuel pump. This allows the flow to go only ONE WAY, towards the fuel distributor. The system pressure setting in the fuel distributor keeps holding pressure in the system and fuel line to the fuel pump. A special fitting on the pump has an internal small plastic/stainless steel ball and a compression spring, which punches the ball against the fuel discharge opening of this fitting. The whole fitting with is contents is called a "CHECK VALVE". Check valves can sometimes not seal properly, due to corrosion or build up on the steel ball. Plastic ball check valves tend to distortions due to their plastic properties, becoming like a four cornered ball. This happens mainly from fuel friction of FLOW and PRESSURE and the rising temperature of the low fuel content in the fuel tank. Water in the fuel speeds up corrosion to the compression spring which may completely disintegrate. The sealing ball goes in every direction which can block or restrict the fuel outlet from the fuel pump. The final result of this is total loss of system pressure. The car becomes extremely hard to start in the morning. This also applies for a car which has driven for more than 10 km. A restarting of the engine is almost impossible, as vapour expansion in the fuel distributor from the hot engine pushes the fuel totally back into the fuel tank. To attempt to restart the engine, due to this temporary air lock in the fuel line and in the fuel distributor, will almost drain the battery.
Shortcut back K-Jetronic site plan.

THE CHARCOAL CANISTER is a tank ventilation unit in a closed loop from the fuel tank towards the vacuum source of the engine. Due to the anti-pollution legislation, all cars must now be fitted with a single or dual stage charcoal canister. HC, or fuel fumes must not enter the atmosphere. Instead they will be sucked off into the engine's intake manifold via a purge valve on the charcoal canister. If the fuel tank slowly becomes empty, the vacuum from the fuel tank sucks air back into the fuel tank via the purge valve from the engine manifold, to replace the fuel used up. The purge valve is a pressure or vacuum equaliser, operated by a diaphragm and seals. The charcoals in the canister is used as a filtering compound for liquids like petrol, and air. Petrol may enter from time to time when the fuel tank is over filled and the vehicle is left in the sun on a hot day. Fuel will expand and follow the breather line into the charcoal canister. On rainy days the overall humidity is about 98% which passes via the filtrations of the charcoal canister back to the fuel tank. The continuous moisture filtration over the years makes this unit internally look like an engine with a severe head gasket leak, with grey slime inside the tappet cover. This brings the charcoal canister out of service for tank ventilation. Excessive vacuum build up inside the fuel tank will restrict the fuel flow and pressure. By removing the fuel cap, a big air suction or air pressure from or into the tank is the result of a blocked tank ventilation which may also be caused by a kinked vent line to the charcoal canister. Checking the charcoal canister operation is quite simple with the INTER-JECT LB-291/F or 2F. Connect the servicing instrument in series into the pressure supply line. Close the diversion valve and start the vehicle. Use a 20 litre container, connect a diversion hose to the valve outlet and insert the hose into the 20 litre container. Open the diversion valve to a point of 40 l/h on the flow meter indicator. See if the flow changes to 35 or a lower indication before the 20 litre container becomes full. Remove the tank ventilation hose from the charcoal canister and at the same time see the flow increase on the flow meter which returns to 40 l/h. The service instrument is talking to you; CHANGE THE CHARCOAL CANISTER as it is blocked.
Shortcut back K-Jetronic site plan.

Shortcut back K-Jetronic site plan.

Explanation:
Recent E-Mail inquire to correct the writer into Pressure and Flow status in the above article Pressure Setting,---  failed because of this following simple explanation:

     THE ENGINE STOPED NO GO after it stoped....