LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1985 >> Forward Control 7.4 W, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Evaporation System >> Component Testing >> Purge Solenoid (CALIF.)

Purge Solenoid (CALIF.)

  1. With ignition "ON" (engine stopped), ground test terminal and apply vacuum at carburetor side of purge solenoid. Vacuum pump should be able to produce 10 in. Hg. If not, remove connector from solenoid and connect test light between harness connector terminals.
  2. If light comes on, faulty solenoid connections or solenoid is the cause. If no light, connect test light from each terminal of connector to ground.
  3. If test light still does not come on, check for open wire to gage fuse. If test light does come on, check for grounded wire at ECM terminal "E". If not grounded, check and/or replace ECM.
  4. If requirements from step 1) are met, check to see if solenoid passes vacuum when test terminal is un-grounded (solenoid de-energized). It should open and keep pump from building up vacuum. If there is no vacuum drop, disconnect solenoid.
  5. If there is still no drop after disconnecting solenoid, replace solenoid. If vacuum does drop after disconnecting solenoid, check for open wire to ECM terminal "E". If OK, check and/or replace ECM.
scientia non olet · About LEMON Manuals