TM 9-4940-568-20
2-60
Table 2-7. Engine Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
12. ENGINE IDLE ROUGH (IRREGULARLY FIRING OR ENGINE SHAKING).
Engine is cold.
Allow engine to warm to operating temperature if engine will not reach operating
temperature. Refer to Troubleshooting Malfunction 20 for Coolant Temperature Below
Normal.
High pressure fuel leak.
Inspect/correct leaks in the high pressure lines and fittings (Para 8-20).
Air in the fuel system.
Check fuel flow/bleed the fuel system (TM 9-4940-568-10).
Fuel pump malfunctioning.
Check/replace fuel pump (Para 8-21).
Plugged fuel filters.
Replace fuel filters (Para 8-18 and 8-19).
Fuel supply restricted.
Check fuel lines and hoses for restriction. Clear any obstructions or debris.
13. ENGINE RUNS ROUGH OR MISFIRING.
Engine is cold.
Allow engine to warm to operating temperature.
Fuel injection lines leaking.
Inspect/correct leaks in the high pressure lines, fittings and injector sealing washer (Para
8-20).
Air in the fuel or the fuel supply is inadequate.
Check the flow through the filters and bleed the system (TM 9-4940-568-10).
Fuel supply restricted.
Check fuel line for restriction. Replace fuel filters (Para 8-18 and 8-19).
Fuel contaminated.
Verify by operating the engine with clean fuel from a temporary tank.
