Rough Engine Idle: Notes
- Remove air cleaner. Install Mag-Tach (J-26925) and check engine idle speed. Reset if necessary. See appropriate article in TUNE-UP Section. Check the injection pump timing. Adjust if necessary.
- Examine injectors for leaks at body or at fuel line connection with engine running. Check for leaks at injection pump-to-high pressure lines. Correct any leaks.
- Perform fuel pump pressure and flow tests. See Testing in this article. Correct any defects in fuel delivery system.
- Remove fuel return line from top of pump. Install short piece of clear plastic tube between return line. With engine running, check for presence of bubbles or foam in tube. Repair any air leaks in system.
- With engine running, loosen fuel line at an injector to bleed a small amount of fuel from the line. If solid fuel appears, check next injector. If foam appears, shut engine off and remove line from injector.
- Move line so that inlet to the injector can be observed. Remove Pink wire to the pump and crank engine. Check injector inlet for bubbles. If bubbles are present, remove injector for testing. Replace if defective.
- If no bubbles are present, connect fuel line and Pink wire. Check remaining injectors in same manner. If engine still idles rough, perform Glow Plug Resistance Procedure.
NOTE:
Rough Engine Idle diagnosis procedure must be performed before Glow Plug Resistance Procedure. Manufacturer recommends the use of Kent-Moore High Impedance Multimeter (J-29125A) for accurate test results.