Removing the injection plug cover
Remove the cover over the waterproof housing in the engine compartment.
Press the retaining clip, disconnect the plug.
Plug (arrow) disconnected from the switch on the throttle shaft. To facilitate troubleshooting, the contacts on the switch are numbered.
Press the plug until the retaining clip clicks into place.
Checking connection with "weight"
Before troubleshooting, you must make sure that the connection of the control unit with "weight" in order.
Disconnect the plug from the control unit.
By connecting the LED tester to the positive pole of the battery and to pin 5 on the plug, make sure that there is a connection with "weight".
Carry out a similar test on pin 25 of the plug.
If there is no connection to "weight", check the passage of the wires according to the electrical diagram and the connection point "masses" on the cylinder block.
Checking the switch on the throttle shaft and control valve (control valve)
Electrical check
Turn on the ignition.
Open the throttle at the drive lever by hand and close again.
At the same time, the control valve should click twice.
If this happens, then the throttle shaft switch and control valve are OK
Control Valve Density Check
Start the engine and leave at idle.
Disconnect the plug on the control valve. RPM should increase as ignition timing shifts to the side "earlier".
Reconnect the plug, the speed should drop.
If so, then the control valve is OK. Otherwise, it should be replaced.
Checking only the switch on the throttle shaft
The described test allows you to determine the presence of a malfunction of the switch on the throttle valve shaft or the valve power supply.
Disconnect the plug on the control valve and connect the LED probe to the plug contacts.
Turn on the ignition, the LED should light up.
Open the throttle with your hand on the drive lever, the LED should turn off.
If both occur, then the throttle shaft switch is OK.
Throttle Shaft Switch Adjustment
If the throttle positioner is replaced with the switch, the switch stop screw must be re-adjusted.
Before starting the adjustment, the throttle positioner tappet must be fully retracted.
To do this, apply a voltage of no more than 6 volts to both upper contacts of the positioner.
This can be done, for example, with a 45-volt battery or by setting the 6-volt range in the charger.
Connect wires, positive wire up.
Wait until the pusher is fully moved.
Connect an ohmmeter to both lower terminals of the throttle positioner.
Insert a 0.5 mm thick measuring probe between the pusher and the stop screw, observing the readings of the ohmmeter.
With the probe inserted, the switch should be on, the ohmmeter reading should be ohms.
Pull out the dipstick again. The switch should open the contacts, the ohmmeter reading should be ∞ Ohm.
If necessary, turn the adjusting screw with a small hexagon wrench and finally fix it with varnish.
Checking the throttle positioner
Throttle positioner (1) can be removed separately. This is necessary if there is a defect in the switch pusher (2). Numeric (3) the throttle stop screw is marked.
Disconnect plug from throttle positioner.
Put the 6-volt range on the charger and apply voltage to both top contacts of the positioner, positive pole on top.
The pusher must fully retract.
Reverse the polarity of the connecting wires (negative wire on top).
The pusher must be fully extended.
If so, then the throttle positioner is OK. Otherwise, it should be replaced.
You can also measure the resistance.
Positioner motor winding resistance between both upper contacts should be 3-20Ω.
The resistance between both lower contacts at open throttle should be ohms.
With the throttle closed, the resistance should be infinite.
Throttle Potentiometer Check
Disconnect the plug from the throttle valve potentiometer.
Connect an ohmmeter according to the table to two of the four pins of the plug.
Throttle potentiometer contacts
If the indicated values do not match the measured values, then the throttle valve potentiometer is defective.
The throttle potentiometer is set at the factory and cannot be disassembled. Here it is removed so that the moving contact can be seen (2) and conductive paths (1) resistance. If it malfunctions, the injection system must be replaced.
Checking the injector
Check with the engine running: it must be warmed up to an oil temperature of at least 60°C. Remove the intake air pipe.
Start the engine and let it idle.
Observe the jet from the injector. It should be uniform and directed towards the throttle valve.
Stop the engine to check the tightness.
With the engine off, no more than two drops per minute should come out.
Further checks should be made if the engine does not start.
Check fuse.
Remove the intake air pipe.
Have an assistant turn the engine over with the starter.
The injector should spray fuel.
If not, disconnect the plug on the top injection system.
Connect an ohmmeter to the two middle terminals on the injection system.
At ambient temperature from +15°C to +30°C, the resistance should be 1.2-1.6 Ohm, otherwise the injector is faulty. Unscrew the bolt and replace the injector.
The voltage supply to the injector should be checked if it does not inject despite the correct resistance.
The additional resistance of the injector should be checked, for this, the plug of the additional resistance must be disconnected on the front right of the rack.
Connect an ohmmeter to the contacts of the plug for resistance.
The measured value should be 3-4 ohms. Connect an LED probe (no other device!) to both middle pins of the disconnected plug.
Turn on the starter, the LEDs should flash, otherwise there is a break in the conductors or the control unit is faulty.
Checking fuel cut when coasting
Remove the air intake pipe.
Start the engine, accelerate quickly above 300 rpm and close the throttle sharply. The clearly visible jet from the injector should at this point be briefly interrupted. In this case, the coasting fuel cut-off device is in order.
If this is not the case, check the switch on the throttle shaft and the control unit.
Checking temperature sensors
Intake air temperature sensor: Disconnect the brown plug at the top of the injection system.
Connect an ohmmeter to both external terminals. Coolant temperature sensor: Disconnect the plug at the sensor at the bottom of the coolant connection.
Connect an ohmmeter to both terminals of the sensor. For both sensors, read the resistance value.
Using the graph below, check whether the resistance of the sensors is consistent with the temperature of the air or coolant.
If the measured values correspond to those given in the graph, then the sensors are in order.
Graph of the dependence of the resistance of the sensors on the temperature of the incoming air (left side) and coolant temperature (right part)
Temperature sensors
1 Heated intake pipe (red insulation)
2 Injection system (blue)
3 Coolant temperature display (black)
Fuel pressure check
The fuel pressure can only be measured with a special tool (In workshop).
If incorrect fuel pressure is suspected, the pressure regulator should be disassembled.
To do this, unscrew the four head screws.
Check if the membrane is damaged and if dirt has entered inside.
Disassembled pressure regulator
1 Lid
2 spring
3 Membrane
4 Adjacent surface
Check damper
The damper may be damaged if the throttle closes jerkily when the gas pedal is released.
When properly adjusted, the lever on the throttle shaft should push the damper pusher 4-4.5 mm down.
Damper adjustment
5. Flat measuring probe
6 Lever on the throttle shaft
7 Pusher
8 Damper
9 Locknut on adjusting screw
If this is not the case, loosen the damper mounting nut.
The damper should be screwed in until the pushrod and lever on the throttle shaft are in the correct position.
From this position, tighten the damper 4½ turns and tighten the nut again.
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