TESTING

EEC System Troubleshooting

There are several things which may be checked if a malfunction of the evaporative emission control system is suspected.

1. Leaks may be traced by using a hydrocarbon tester. Run the test probe along the lines and connections. The meter will indicate the presence of a leak by a high hydrocarbon (HC) reading. This method is much more accurate than visual inspection which would only indicate the presence of a leak large enough to pass liquid.
2. Leaks may be caused by any of the following:
   1. Defective or worn hoses.
   2. Disconnected or pinched hoses.
   3. Improperly routed hoses.
   4. A defective filler cap or safety valve (sealed cap system).

      WARNING
      If it becomes necessary to replace any of the hoses used in the evaporative emission control system, use only hoses which are fuel resistant or are marked EVAP.

3. If the fuel tank collapses, it may be the fault of clogged or pinched vent lines, a defective vapor separator, or a plugged or incorrect filler cap.
4. To test the filler cap (if it is the safety valve type), clean it and place it against the mouth. Blow into the relief valve housing. If the cap passes pressure with light blowing or if it fails to release with hard blowing, it is defective and must be replaced.

   WARNING
   Use the proper cap for the type of system used; either a sealed cap or safety valve cap, as required.