Faulty start valve causes difficulty starting the engine (both cold and hot), transient faults and high fuel consumption.
A time-delay thermal switch limits the fuel injection time by the start valve depending on the engine temperature. Attention: Perform the check in the following order.
Checking the supply voltage
Disconnect from ignition distributor (terminal 4) high voltage wire (center wire) and short it to ground; if necessary, use an auxiliary wire with the same cross-section for this.
Disconnect the plug from the starting fuel valve and connect a voltage indicator or test lamp to the plug contacts.
Disconnect plug -2- from time delay thermostat -1-.
Connect the green/white wire of the time-delay thermostat with the auxiliary wire to ground.
Caution: Do not ground the red/black wire. Risk of short circuit!
Turn on the starter, the voltage indicator LED should light up, otherwise, in accordance with the electrical diagram, find and repair a break in the wiring.
Removing the starting fuel valve
Disconnect the plug from the starting fuel valve.
Unscrew the fuel line from the starting valve.
Caution: The system is under pressure, so cover the connection point with a cloth and slowly release the hollow bolt. If the starting fuel valve is removed only for inspection, do not unscrew the fuel line.
Unscrew and remove the starting fuel valve from the intake manifold.
Examination
Remove the fuel start valve.
Connect the plug to the start valve, the fuel hose is connected. The plug from the time delay thermostat remains disconnected and the green white wire is shorted to ground, see Figure 25-1112.
Insert the starting fuel valve into a measuring container.
Switch on the starter for a short time. The starting valve must inject fuel in the form of a regular cone-shaped jet.
Dry the start valve spray.
Within one minute, not a single drop of fuel should appear on the atomizer. Externally, the start valve must also not be wet, otherwise the valve must be replaced.
Installing the starting fuel valve
Attach the starting fuel valve together with a new seal and screw it on.
Connect the plug to the time delay thermostat.
Connect high voltage wire to terminal 4.
If removed, tighten fuel hose to start valve to 10 Nm. Connect plug.
Checking the thermal relay with a time delay
To carry out the test, the engine must be cold, the temperature of the coolant is less than + 30°C. Remove the thermostat and cool in a bath of water.
Disconnect from ignition distributor (terminal 4) high voltage wire (center wire) and short it to ground, if necessary using an auxiliary wire with the same cross section.
Disconnect the plug from the starting fuel valve and connect a voltage indicator or test lamp to the plug contacts. Checking the thermal relay is carried out through the electrical connector of the starting fuel valve.
Turn on the starter for about 10 seconds, the voltage indicator LED, depending on the temperature of the thermal relay, should light up for 1-8 seconds. The first ignition, depending on the ambient temperature, must be within the prescribed range, see diagram. For example, the coolant temperature is +10°C. Then the duration of the inclusion should be 2.0-5.5 seconds.
If the prescribed value is not reached, replace the time delay thermostat.
To replace, disconnect the plug from the thermostat and unscrew the thermostat. Screw in a new time delay thermostat and connect the plug to it.
Connect the high voltage wire to the ignition distributor and the plug to the fuel start valve.
Check coolant level, top up if necessary.
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