HYOSUNG AQUILA 250 FI, Service Manual, Page: 69 / 90

68
7-1-3 SERVICING INFORMATION
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ENGINE
Complaint Symptom and possible causes Remedy
Engine will not
start or is hard to
start. Compression too low
1. Tappet clearance out of adjustment.
2. Worn valve guides or poor seating of valves.
3. Mistimed valves.
4. Excessively worn piston rings.
5. Worn-down cylinder bore.
6. Starter motor cranks too slowly.
7. Poor seating of spark plugs.
Plug not sparking
1. Fouled spark plugs.
2. Wet spark plugs.
3. Defective ignition coils.
4. Open or short in high-tension cord.
5. Defective pick-up coil.
6. Defective ECU.
7. Open-circuited wiring connections.
No fuel reaching the intake manifold
1. Clogged fuel filter or fuel hose.
2. Defective fuel pump.
3. Defective fuel pressure regulator.
4. Defective fuel injector.
5. Defective fuel pump relay.
6. Defective ECU.
7. Open-circuited wiring connections.
Incorrect fuel / air mixture
1. Defective fuel pump.
2. Defective fuel pressure regulator.
3. Defective pick-up coil.
4. Defective IAP sensor.
5. Defective ECU.
6. Defective ET sensor.
7. Defective IAT sensor.
Adjust.
Repair or replace.
Adjust.
Replace.
Replace.
See electrical section.
Retighten.
Clean.
Clean and dry.
Replace.
Replace.
Replace.
Replace.
Repair or replace.
Clean or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Check and repair.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.