Section 03
ENGINE
Subsection 02
(TROUBLESHOOTING)
03-02-16
VMR2004_125_03_02A.FM
SYMPTOM
ENGINE SUDDENLY TURNS OFF.
CONDITION
NORMAL USE.
Test/Inspection
3. Check fuel supply to engine intake.
a. Fuel valve is switched off.
Turn on fuel valve.
b. Run out of fuel.
Turn fuel valve to “RES” position and refill.
c. Poor quality and/or wrong fuel.
Clean from contamination and use appropriate fuel (refer to TECHNICAL DATA).
d. Carburetor contaminated.
Clean jets and carburetor float chamber from contamination.
e. Fuel line clogged and/or bent.
Clean fuel supply from contamination and/or replace defective part(s).
f. Fuel supply insufficient at high RPM.
Clean fuel supply from contamination.
4. Perform engine leak test. Refer to ENGINE LEAK TEST procedure. Check for
possible piston seizure.
a. Damaged head gasket and/or seal and/or leaking inlet/exhaust valve(s).
Replace and/or repair defective parts.
5. Piston seizure (piston ring(s) damaged and/or cylinder shows grooves).
a. Spark plug heat range is too low.
Replace damaged parts and install spark plug with appropriate heat range
(refer to TECHNICAL DATA).
b. Compression ratio is too high.
Install genuine parts.
c. Poor oil quality.
Use a high quality oil.
d. Leaks at air intake manifold (engine gets too lean).
Retighten screws or replace air intake manifold.
e. Contamination (like sand) through engine intake.
Replace defective part(s) and use new air filter.
6. Melted and/or perforated piston dome; melted section at ring end gap.
a. Spark plug heat range is too low.
Install recommended spark plug (refer to TECHNICAL DATA).
b. Coolant less than recommended level (engine gets too hot).
Repair cooling circuit and/or refill with recommended liquid.
