Yanmar MP series Service Manual page 101

TROUBLESHOOTING
FUEL SYSTEM TROUBLESHOOTING CHART
Use this troubleshooting chart to assist in the diagnosis of the fuel system prior to removing the fuel injection
P'-"nP.
YAMMAR.
MP
Pump
Service
Manual
Complaint
1. Engine
won't Start.
Cause
(1) No fuel in the fuel tank.
(2) Fuel tank valve is closed.
(3) Fuel line or valve is clogged.
(4)
Fuel filter element is clogged.
(5) Air in fuel lines.
(6) Fuel feed pump inoperable.
(7) Fuel has gelled.
(1) Stop solenoid is Inoperative.
(2) Throttle control inoperative.
(3) Air in fuel lines.
(4) Low cranking speed.
(5) Internal failure of injection pump.
(6) Governor is damaged.
(7) Injection pump coupling, gear or key is damaged.
(8) Lifter is seized.
(9) Cold start device is inoperative.
(1 0) Transmission shaft is seized. Gear slip.
(1) Compression leakage past injector.
(2) Fuel leakage from nozzle.
(3) One or more nozzles are sticking open or closed.
(1) Injection pump is installed incorrectly.
(2) lnjection timing is excessively advanced or retarded due to
failed key or coupler.
(3) Internal failure of injection pump.
delivered to
injection
Pump-
Fuel
delivered to
injection
Pump.
inoperative.
lnjection
timing is
defective.
Correction
Fill with fuel.
Open.
Clean complete fuel system.
Disassemble and clean, or
replace element. Find and repair
source of debris in fuel.
Locate air leak using clear fuel
line and repair.
Replace.
Replace with a fuel for cold
weather or use fuel heater.
Determine cause and repair or
replace solenoid.
Repair or adjust.
Locate air leak using clear fuel
line and repair.
Check battery, starter motor or
internal engine components for
failure.
Remove pump and repair.
Remove governor and repair or
replace.
Replace.
Check lube oil supply and oil
pump. Repair pump.
Repair device.
Repair pump.
Replace nozzle seat and tighten
retainer to specifications.
Tighten case nut to specification.
Determine cause of nozzle
failure and repair.
Reinstall pump and time engine.
Replace key or coupler.
Remove pump and repair.