Troubleshooting
The checks described below assume that the engine has no mechanical damage, but has stalled and will not start.
For a diesel engine, the main condition is that the engine warms up when starting up until the preheater indicator lamp goes out.
Does the starter crank the engine?
If it does not scroll or scrolls weakly, read the section «Sources of electrical equipment malfunction». If the motor cranks, it is necessary to answer the following questions for further troubleshooting:
Is there spark in the spark plugs?
Remove the wire from the spark plug, unscrew the spark plug, reconnect the wire and lay it on bare metal. Have an assistant turn the engine over. When doing this, do not touch the ignition wire and spark plug, see «LEZ Ignition Precautions» in chapter «Ignition system». Do sparks fly? If not, see section «Sources of ignition malfunction».
Is fuel injected in a gasoline engine?
Disconnect the injection fuel supply hose (multipoint injection) and put it in the container (cover cap from the emergency stop sign). Ask the assistant to briefly turn on the starter.
Gasoline appeared in the tank - the power supply system is working, and the nozzles may be defective.
No gasoline - read more about problems in the power system.
Is diesel fuel getting to the injector?
Use SW 17 wrench to unscrew the nut of the fuel line to the injector. Have an assistant turn on the starter. Is fuel coming out of the injector? If yes, then the fuel supply is probably OK. Then read the next question. If there is no fuel, read «Sources of fuel failure».
Does the diesel preheater work?
Connect a test lamp to the main electrical connection on the glow plugs; and the other wire of the lamp to ground. Have an assistant turn the ignition key to position «warming up».
Did the lamp light up? If it does not light up even though the engine is cold, the preheater is faulty. If it is on, the power supply to the glow plugs is OK. However, the spark plugs themselves may be faulty. Read about it in the section «Sources of malfunction of the preheater».
Checking a gasoline engine by external inspection
- Has the wire plug on the ignition or injection system components slipped off?
- Check the tightness of the connection of the high voltage wires and whether they are well put on the spark plugs (the ignition must be switched off!).
- Are all the low pressure hoses in the engine compartment fitted to their respective fittings?
- Is there any condensation on the ignition coil or ignition system components? All components of the ignition system must be dry.
- Is there a smell of gasoline in the engine compartment? Is the fuel hose loose or loose?
Sources of malfunctions of electrical equipment of gasoline and diesel engines
- The control lamps go out when the key is turned: the battery is discharged or weakened due to «age», there is a possible short circuit in the starter.
- The control lamps remain lit when the key is turned: the white wire has come off the starter magnetic switch, the magnetic switch is faulty, the starter is faulty or the graphite brushes are worn out, or the contact terminal B2 in the ignition switch is faulty.
- The control lamps do not light up: the battery is completely discharged, the main starter wire has fallen off, or the battery terminals have weakened and oxidized.
Sources of fuel supply problems
If fuel does not flow during the described check from the injection system and, accordingly, diesel injectors, the following causes of the malfunction may be:
All engines
- No fuel in the tank (don't laugh, check it out!).
- Broken or clogged fuel line.
- Fuel filter clogged.
Gasoline engines
- The electric fuel pump is not working.
- Check all electrical pin connections. Maybe a separate wire of the multi-pin connection has jumped out or broken?
Diesel only
- The shut-off valve of the diesel high-pressure fuel pump is faulty and blocks the flow of fuel to the injectors.
- When assembling in the diesel high-pressure fuel pump, two hollow screws for supplying and discharging fuel were mixed up. The hollow fuel bleed screw is marked «OUT».
- Clogged fuel filter or fuel lines, or fuel thickened in cold weather. This can be determined by the transparent fuel lines in the engine compartment. If the wires are empty or there are large air bubbles, then the fuel supply is interrupted.
Note. Recommendation: Other sources of faults, which are much less common in the fuel and injection systems of petrol and diesel engines, can be found in the troubleshooting guide in the respective chapter.
Sources of ignition malfunctions
- Are all connectors connected correctly in the area of the ignition coil, control unit and, accordingly, the ignition module?
- Are there any cracks in the ignition distributor cap or ignition coil housing, traces of soot from spark breakdown?
- As a last resort, only check the ignition system remains, see the relevant chapter in section «Troubleshooting in the ignition system».
Sources of malfunctions of the preheater
The preheater can be checked with a test lamp. In the event of a defect in the pre-heater, see the relevant chapter for test methods.
In any case, a good engine can be started without the use of a preheater by cranking it longer with the starter, unless the outside temperature is below zero. If lower, then only towing can help.