Mechanical Diagnosis
Diagnosing Unit Conditions
|
CONDITION |
POSSIBLE CAUSE |
REMEDY |
|---|---|---|
|
Engine will not crank |
Electrical problem |
Check and repair electrical system |
|
Defective starter solenoid |
Replace solenoid |
|
|
Defective starter |
Repair starter |
|
|
Water in cylinders |
Check for hydrostatic lock. Remove injectors and turn engine slowly |
|
|
Starter motor turns but engine does not crank |
Starter clutch defective |
Replace |
|
Engine cranks but fails to start |
Voltage falls below 6 Vdc at ECU while starter cranking |
Repair cause of low voltage at ECU while starter cranking |
|
Problem with ECU controlled engine function |
Use YSAD engine diagnostic tool to diagnose problem |
|
|
Electric fuel pump not energized |
Check 8DF and CHFP circuits |
|
|
Electric fuel pump defective |
Replace electric fuel pump |
|
|
Air in fuel system |
Bleed air |
|
|
Compression low |
Overhaul engine |
|
|
Air cleaner clogged |
Replace air filter |
|
|
Exhaust plugged |
Clean exhaust |
|
|
Engine stops after starting |
Air in fuel system |
Bleed fuel system |
|
Fuel filter obstructed |
Replace filter element |
|
|
Vent of fuel tank obstructed |
Unclog vent |
|
|
Clogged fuel tank or fuel lines |
Clean fuel tank and fuel lines |
|
|
High head pressure |
Eliminate cause of high head pressure |
|
|
Engine does not develop full power |
Air intake system clogged |
Clean air intake system |
|
Fuel tank vent clogged |
Unclog vent |
|
|
Clogged fuel tank or fuel lines |
Clean fuel tank and fuel lines |
|
|
Insufficient fuel volume leaving filter |
Check for dirty filter or air in system |
|
|
Air cleaner clogged |
Replace air filter |
|
|
Delivery of electric fuel pump insufficient |
Repair pump |
|
|
Problem with ECU controlled engine function |
Use YSAD engine diagnostic tool to diagnose problem |
|
|
Compression low or unbalanced |
Overhaul engine |
|
|
Engine speed too high |
Problem with ECU controlled engine function |
Use YSAD engine diagnostic tool to diagnose problem |
|
Engine fails to stop when unit is OFF |
Problem with ECU controlled engine function |
Use YSAD engine diagnostic tool to diagnose problem |
|
Engine knocks heavily |
Air in system |
Bleed fuel system |
|
Wrong fuel |
Change fuel |
|
|
Compression too low |
Overhaul engine |
|
|
Valve out of adjustment |
Adjust valves |
|
|
Fuel return line plugged |
Remove return line restriction |
|
|
Rod or main bearing worn |
Replace rod or main bearings |
|
|
Engine runs hot |
Dirty radiator |
Wash radiator |
|
Coolant level is low |
Add coolant |
|
|
Cooling system heavily scaled |
Cleaning cooling system |
|
|
Cylinder head gasket leaks |
Replace cylinder head gasket. Use correct gasket |
|
|
Faulty thermostat |
Check or replace thermostat |
|
|
Loose or worn water pump belt |
Replace belt |
|
|
Oil pressure low |
Insufficient oil in pan |
Add oil |
|
Faulty oil pressure switch |
Check oil pressure switch. Replace if necessary |
|
|
Oil control valve defective |
Check oil pressure control valve |
|
|
Worn oil pump, camshaft, main or connecting rod bearings, loose oil gallery plug |
Repair engine |
|
|
High oil consumption |
10 hour engine break in running was not successfully completed |
Run unit for 10 hours in continuous high speed with varying load. |
|
Oil leakage |
Check and eliminate possible causes at rocker arm cover, oil lines, oil filter, front timing cover or crankshaft seals |
|
|
Damaged valve seals |
Replace seals on valve stem |
|
|
Worn valve stem |
Replace valves |
|
|
Broken piston rings or cylinder bore worn or scored |
Have engine repaired and rebored. Replace broken piston rings |
|
|
Clogged air cleaner system |
Unclog air cleaner |
|
Engine Emits Excessive Smoke
|
White Smoke |
Black Smoke |
Blue Smoke |
|
Fuel is not burning |
Excessive Fuel to Air Ratio |
Oil Consumption |
|
|
|