Compuvalve Checklist

If diagnostic results from Pinpoint Tests indicate a suspect compuvalve, complete all items listed below before replacing the compuvalve.
- Verify ALT fuel switch status. REFER to Description and Operation. Description and Operation
- Ensure proper communication ability with EEC and compuvalve.
- Confirm that MAP line is not loose, kinked, or restricted.
- Check harness and connection integrity.
- Verify EEC calibration is from current Bi-Fuel code.
- Verify B+ to compuvalve.
- Verify adequate fuel level at the tank sending unit to permit engine operation in ALT fuel mode.
- Confirm that fuel filter is not installed backward.
- Verify base vehicle does not have a secondary ignition operation concern.
- Check for any applicable TSB and Special Service Messages.

Common causes of compuvalve misdiagnosis:
- MAP elbow loose
- High FAP - from vaporizer malfunction
- Low FAP due to lockoff fault
- Incorrect interpretation of DTCs
- Misfire - due to O-rings
- Compuvalve replaced without checking HPS circuit for high resistance

Compuvalve Replacement
If all items on this checklist have been completed and compuvalve replacement is required it is important to always observe the following:

CAUTION: Before replacing the compuvalve, always be sure the battery and the red connector C495 are disconnected when removing or installing a compuvalve. The reason for this procedure is that when reconnecting the compuvalve connector to the compuvalve it is possible to obtain a partial insertion of the connector into the compuvalve with the signal pins offset one pair of pins laterally. Although full insertion is not possible and the misalignment will be immediately noticed and corrected by the technician, the partial insertion brings into contact a 12-volt power socket with a 5-volt power pin. If the battery and the red connector C495 have not been disconnected this partial insertion will result in a permanently inoperable compuvalve.