Yanmar MP series Service Manual page 100

TROUBLESHOOTING
INTRODUCTION
This section of the Service Manual includes troubleshooting procedures and troubleshooting charts used in
the diagnosis of the fuel injection pump and fuel system problems.
TROUBLESHOOTING
Troubleshooting a fuel system related problem involves:
Identifying the problem accurately.
Duplicating the problem.
Correctly identifying the cause of the problem.
Correcting the problem.
Eliminating the cause of the damage.
Repairing the damage.
Verify corrections made have corrected the initial problem.
Preliminary Checks
To quickly and accurately troubleshoot fuel system problems, the following preliminary checks should be
performed before the fuel injection pump is removed. When possible provide troubleshooting assistance to
the customer, before the fuel injection pump is removed. This will prevent unnecessary costs that can result
from an incorrect diagnosis.
If the pump is removed prematurely, the initial cause of the problem may never be known.
Check the mechanical condition of the engine.
Check the condition of the fuel type and quality, fuel flow, and fuel pressure throughout the fuel system.
Check for restrictions and leaks throughout the fuel system.
Verify fuel injection timing is within specifications.
Verify fuel nozzle operation and nozzle spray condition.
Fuel Injection Pump Repair
If the fuel injection pump is found to be faulty, remove it from the engine for repair.
It is very important that the root cause of the failure is eliminated before installing and I or repairing the fuel
injection pump.
MP Pump Service Manual