Schematic diagram of the fuel injection system «K-Jetronic»:
1 - fuel tank; 2 - fuel pump; 3 - fuel accumulator; 4 - fuel filter; 5 - dispenser-distributor of fuel; 6 - supply pressure regulator; 7 - control pressure regulator; 8 - safety switch; 9 - pressure disk of the air flow meter; 10 - throttle valve; 11 - adjusting screw idling; 12 - valve for additional air supply; 13 - starting nozzle; 14 - thermal time relay; 15 - nozzles.
Features of the device and the operation of the fuel injection system «K-Jetronic» Bosch companies are described in subsection «fuel injection system» section «Six-cylinder engine».
Throttle position adjustment
Disconnect the throttle control link from the lever.
Loosen nut 3 and tighten the bolt so that the gap between stop 1 and throttle control lever 2 becomes 1±0.5 mm.
Loosen the set bolt 4 and move the throttle valve in the housing so that there is no gap between the throttle valve and the housing wall.
Tighten the set bolt 4, then tighten the bolt 3 by 1 turn; at the same time, the throttle valve must move without jamming and not touch the walls of the housing. Tighten nut 3.
Connect the throttle control rod to the lever and adjust the throttle control rod if necessary.
Engine idle adjustment
Warm up the engine.
Adjusting screw set the crankshaft speed within 900±50 rpm.
Check the carbon monoxide content (SO) in exhaust gases, which must correspond to the value specified in subsection «Detailed Specifications».
Remove if necessary (using mandrel 131012 for «3181») quality adjusting screw plug (composition) mixture and a special mandrel (130010 for «320i» or 130020 for «318i») achieve the proper content of CO in the exhaust gases.
During adjustment, do not increase the engine speed.
At the end of the adjustment, put a new plug in the hole for the mixture adjustment screw (using mandrel 131013 for «318i»).
Checking the fuel dispenser
Fuel dispenser-distributor of the fuel injection system of car engines of models: A - «320i»; IN - «318i»:
1 - dispenser-distributor of fuel; 2 - air flow meter; 3 - gasket; 4 — the bottom case of a regulator of a mix; 5 - pressure disk of the air flow meter; 6 - air supply casing; 7 — silent blocks; 8 - plug quality adjusting screw (composition) mixtures.
Remove the plastic air supply cover.
Operate the fuel pump by switching on the ignition for a few seconds and at the same time lift the pressure plate of the air mass meter manually or with a magnet. At the same time, a uniform resistance should be felt throughout the entire stroke of the pressure disc. Moving the pressure disc down should not require force.
When the pressure disk touches the walls of the air flow meter housing, unscrew the central screw securing the pressure disk and center it by placing a 10 mm thick gasket at four points around the circumference.
Make sure the pressure disc is level with or no more than 0.5mm below the start of the flared cone of the air mass meter housing.
If necessary, adjust the position of the pressure plate of the air flow meter by bending the spring clip, having previously removed the lower housing of the mixture regulator.
Checking the starter injector
Disconnect the thermal time relay plug and connect the brown wire to the black stripe (terminal «W») on «mass».
Disconnect the wire from the terminal «50» starter relay.
Remove the starter injector from the intake manifold.
Connect Lead «30» start relay with terminal «+» battery.
In this case, the atomizer of the starting injector should atomize the fuel.
If the pilot injector needle does not open, or if drops of fuel flow out of the nozzle nozzle after the needle is closed, replace the pilot injector.
Checking the thermal time switch
Disconnect the plug connector of the thermal time switch.
Connect a test lamp with one wire to the terminal «+» battery and the other to the plug «W» thermal timer.
When the coolant temperature is above plus 15°C, the control lamp should not light up, and when the coolant temperature is below plus 15°C, it should light up.
Checking the performance of the fuel pump
Disconnect the fuel drain hose from the fuel dispenser.
Attach a hose to the fuel drain fitting of the fuel dispenser, and place a beaker under its free end.
Operate the fuel pump and check its performance, which should be equal to 750 cm3 of fuel in 30 seconds.
Pressure test
Connect one pressure gauge hose with 2-way cock 133060 to the control pressure fitting of the fuel dispenser and the other to the control pressure line.
Disconnect the connectors of the control pressure regulator and the auxiliary air supply valve.
Checking the control pressure on a cold engine
Pilot pressure on a cold engine should only be checked if it is difficult to start a cold engine or if the engine does not run when warm.
Disconnect the mixture regulator connector.
Turn on the ignition and open the two-way valve of the pressure gauge
Read the pressure gauge and compare the value obtained depending on the temperature of the coolant with the graph given on page (see section «Six-cylinder engine»).
If the measured pressure is below normal, the control pressure regulator is defective.
If the measured pressure is higher than normal, this indicates insufficient fuel drain or a malfunction of the pilot pressure regulator. Check the condition of the drain line, install a new pilot pressure regulator and check its operation.
Checking the pilot pressure on a hot engine
Connect the control pressure regulator plug.
Turn on the ignition by first opening the two-way cock of the pressure gauge and disconnecting the plug connector of the mixture regulator.
3 minutes after the engine stops, the control pressure should be within the range of 2.7-3.1 kg / cm2.
Connect the connectors of the auxiliary air supply valve and the mixture regulator.
Start the engine.
At idle, measure the control pressure, which should be in the range of 3.4-3.8 kg / cm2.
If the measurement result is below normal, check the condition of the auxiliary air valve plug and the control pressure regulator.
If the measurement result is higher than normal, this indicates a defective vacuum hose, insufficient fuel drain or a malfunction of the control pressure regulator.
Checking fuel pressure on a cold or hot engine
With the engine stopped, close the two-way cock of the pressure gauge.
Disconnect the mixture regulator connector.
Turn on the ignition and measure the fuel supply pressure, which should be between 4.5-5.2 kg/cm2.
Causes of insufficient fuel supply pressure can be:
- leakage of fuel lines and their connections;
- contamination of the fuel fine filter;
- insufficient fuel supply by the fuel pump;
- violation of the fuel pressure regulation.
The causes of increased fuel supply pressure are:
- insufficient fuel drain;
- violation of the adjustment of the fuel pressure regulator in the system or jamming of its plunger.
The fuel supply pressure is regulated by selecting the thickness of the shims installed on the plunger of the fuel pressure regulator in the system.
Thickness of adjusting washers, mm | Change in fuel supply pressure, kg/cm2 |
0,1 | 0,06 |
0,5 | 9,3 |
Checking the tightness of the system with the engine stopped
Open the two-way valve of the manometer.
Turn on the ignition.
Disconnect and then reconnect the mixture control connector.
Switch off the ignition.
After a few minutes, the pressure in the system should be at least 1.7 kg/cm2.
The reasons for the pressure drop in the system below 1.7 kg/cm2 may be: leakage of pipelines and their connections, fuel pump check valve or fuel accumulator.
Checking the condition of the injection nozzles
Unscrew the nozzles from their sockets.
Lift the pressure plate of the air mass meter manually or with a magnet with residual pressure in the system.
Make sure that no more than one drop of fuel flows out of the injector nozzles within 15 seconds.
Checking the auxiliary fuel supply valve
Disconnect the control pressure regulator connector.
Disconnect the hoses from the auxiliary air supply valve fittings.
At a coolant temperature of about plus 20°C, make sure that that the opening is half open.
By connecting the hoses to the auxiliary air supply valve.
Connect the control pressure regulator plug.
Switch on the ignition and start the engine.
After 5 minutes of engine operation, the through hole should be completely blocked.
Otherwise, replace the auxiliary air valve.
Possible malfunctions of the fuel system and methods for their elimination
See section «Six-cylinder engine».