Dieseling/Run-on

SYMPTOM DESCRIPTION:

Engine continues to run after key is turned "OFF", but runs very roughly. If engine runs smoothly, check ignition switch and adjustment.

SYSTEM OR COMPONENT TO CHECK

FUEL
CHECK:
INJECTOR LEAKAGE: Hookup a fuel pressure gauge, remove and block off return line and power up fuel pump (engine OFF). Fuel pressure should stabilize and remain constant. Perform injector balance test, check for weeping or dribbling injectors, all injectors should exhibit clean cutoff of spray pattern

ENGINE
CHECK:
IDLE SPEED: Excessively high. Stuck or defective Idle Air Valve

EMISSIONS
CHECK:
EVAPORATIVE: Purge valve and fuel tank venting