Technical Service Bulletins
|Publication Date: MAY 15, 2001|
1994-2001 F-150, F-250 LD
1995-2001 E-250, E-350
1999-2001 SUPER DUTY F SERIES
This article will be used as an aid in diagnosis to avoid unnecessary replacement of the compuvalve on bi-fuel vehicles after normal diagnosis has determined the compuvalve may be faulty.
Complete the normal diagnostic methods and pinpoint tests. Should the conclusion be after normal diagnosis to replace the compuvalve, then follow the compuvalve Pre-Replacement Checklist (below) before replacing the compuvalve.
Glossary Of Terms
- ALT – Alternate Fuel Mode
- FAP – Fuel Absolute Pressure
- HPS – High Pressure Solenoid
- VCL – Vehicle Communications Link
- AFCM – Alternate Fuel Control Module
- WDS – Worldwide Diagnostic System
- DTC – Diagnostic Trouble Code
- MAP – Manifold Absolute Pressure
- LPG – Liquid Propane Gas
- EEC – Electronic Engine Control
|NOTE:||THE FOLLOWING IS A LIST OF KNOWN MIS-DIAGNOSIS OF THE COMPUVALVE REPLACEMENT ON BI-FUEL VEHICLES.|
- MAP line loose.
- High FAP from vaporizer breakdown.
- Incorrect interpretation of DTCs.
- VCL replacement due to harness faults.
- Misfire due to leaking O-rings.
- Compuvalve replaced without checking HPS circuit for correct resistance.
- Low FAP due to lockoff fault.
- LPG fuel filter in backward.
COMPUVALVE PRE-REPLACEMENT CHECKLIST
- Check communication ability with EEC, AFCM/compuvalve and VCL and compuvalve. Follow the Powertrain Control/Emissions Diagnosis (PC/ED) Workshop Manual procedures for the appropriate vehicle.
- Check MAP line. Follow normal diagnostic methods and visual checks.
- Check harness and connection integrity. Follow normal diagnostic methods, basic circuit checks and harness connections.
- Check current bi-fuel EEC calibration code. Refer to WDS.
- Check fuel gauge with fuel selector switch in ALT position for fuel level.
- Check power to compuvalve. Power to the compuvalve is indicated by the following fuel selector switch light status: On steady = OK, On then Off or Flashing (regular and irregular) indicated fault.
- Check that the arrow on the LPG fuel filter is pointing in the direction of fuel flow.
- Check base vehicle. Run vehicle in gas mode (e.g., borderline secondary ignition). Follow normal diagnostic methods.
- Check other applicable TSBs and special service messages.
- Verify ALT fuel switch status. Refer to Section 1 of the appropriate PC/ED Workshop Manual.
OTHER APPLICABLE ARTICLES:
490000, 602300, 603300, 608000, 609000, 611000, 623000, 690000, 698298