HYOSUNG MS3 250 Sercie Manual page 222

Complaint
Engine idles poorly.
Engine stalls often
Symptom and possible causes
1. Tappet clearance out of adjustment.
2. Poor seating of valves.
3. Defective valve guides.
4. Worn down camshafts.
5. Too wide spark plug gap.
6. Defective ignition coil.
7. Defective pick-up coil.
8. Defective ECU.
9. Defective TP sensor.
10. Defective fuel pump.
11. Imbalanced throttle valve or SAV solenoid.
12. Damaged or cracked vacuum hose.
Incorrect fuel / air mixture
1. Defective IAP sensor or circuit.
2. Clogged fuel filter.
3. Defective fuel pump.
4. Defective fuel pressure regulator.
5. Defective WT sensor.
6. Defective thermostat.
7. Defective IAT sensor.
8. Damaged or cracked vacuum hose.
Fuel injector improperly operating
1. Defective fuel injector.
2. No injection signal from ECU.
3. Open or short circuited wiring connection.
4. Defective battery or low battery voltage.
Control circuit or sensor improperly operating
1. Defective ECU.
2. Defective fuel pressure regulator.
3. Defective TP sensor.
4. Defective IAT sensor.
5. Defective pick-up coil.
6. Defective WT sensor.
7. Defective fuel pump relay.
Engine internal parts improperly operating
1. Fouled spark plug.
2. Defective pick-up coil or ECU.
3. Clogged fuel hose.
4. Tappet clearance out of adjustment.
SERVICING INFORMATION 9-4
Remedy
Adjust.
Replace or repair.
Replace.
Replace.
Adjust or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Adjust.
Replace.
Repair or replace.
Clean or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Repair or replace.
Repair or replace.
Replace or recharge.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace.
Clean.
Adjust.