Contents Wiring diagrams Section: Testing & Diagnostics All sections

Engine Controls - Tests W/o Codes: NVH GMC Vandura P3500

ENGINE STARTS, IDLES ROUGH WITHOUT UNUSUAL NOISE OR SMOKE

Possible CauseCorrection
Incorrect slow idle adjustment.Reset slow idle adjustment. See ADJUSTMENTS article.
Leaking injection line.Check fittings and/or replace line.
Plugged fuel return line.Remove restrictions.
Air in lines to nozzles.Check line fittings.
Air in injection pump.Check pump fittings and pump operation.
Faulty nozzle.Replace nozzle. See I - SYS/COMP TESTS article.
Improper or contaminated fuel.Remove and replace fuel.
Uneven fuel distribution.Check fuel delivery system.

ENGINE STARTS, IDLES ROUGH WITHOUT UNUSUAL NOISE OR SMOKE

ENGINE STARTS AND IDLES WITH EXCESSIVE NOISE AND/OR SMOKE

Possible CauseCorrection
Incorrect pump timing.Adjust pump timing. See ADJUSTMENTS article.
Restricted air filter.Check and/or replace air filter.
Air in injection lines to nozzles.Check fittings on lines.
Faulty nozzle.Replace nozzle. See I - SYS/COMP TESTS article.
Improperly installed high pressure lines.Remove lines, and reinstall properly.

ENGINE STARTS AND IDLES WITH EXCESSIVE NOISE AND/OR SMOKE

"RAPPING" NOISE FROM CYLINDERS

Possible CauseCorrection
Air in fuel system.Check fuel delivery system for leaks.
Air in high pressure lines.Check fittings for leaks.
Nozzle sticking in open position.Inspect and/or replace nozzle.
Low nozzle opening pressure.Check nozzle operation. See I - SYS/COMP TESTS article.

"RAPPING" NOISE FROM CYLINDERS

EXCESSIVE NOISE WITH BLACK SMOKE

Possible CauseCorrection
Incorrect pump timing.Adjust pump timing. See ADJUSTMENTS article.
Incorrect pump housing pressure.Check pump for internal leaks.
Defective injection pump.Replace injection pump. See I - SYS/COMP TESTS article.

EXCESSIVE NOISE WITH BLACK SMOKE