Housing Pressure Cold Advance (HPCA) Diagnosis

Cold Advance And Shutdown Solenoids:

An inoperative housing pressure cold advance solenoid may cause white smoke and excessive noise on cold start.

With engine temperature below 27°C (80°F), start and idle engine. Disconnect housing pressure cold advance solenoid connector. If system is operating, a decrease in engine noise and a drop in engine speed will be noticed.

If this does not occur, the system should be diagnosed as follows:

1. Perform the cold advance system electrical check.
2. If the cold advance system electrical circuit is operating, remove injection pump cover.
3. Ground pump cover with a fused jumper wire, momentarily touch the housing pressure cold advance solenoid terminal and listen for a "click" sound. If solenoid operates, check for a restriction in the fuel return line.
4. If solenoid does not operate, remove the return line connector from the injection pump cover. Determine if the spring loaded valve, in the return line connector is stuck. If valve is stuck, replace the return line connector.
5. If valve moves, use an ohmmeter to check for continuity between solenoid housing and injection pump cover. If more than 0.5 ohms, repair poor ground connection.
6. If ground connection is "OK", replace housing pressure cold advance solenoid.