1. Bring the engine to a temperature of 80° F (27° C).
2. If available, install a diesel injection timing meter (J 33300).
3. Start and operate the engine, noting its speed.
4. Remove the electrical connector for the HPCA solenoid and note the engine speed:
• If engine speed decreases (and timing retards), the solenoid action is correct.
• If engine speed does not decrease (no timing retard), do the following things:
A. Measure the voltage at the HPCA solenoid connector:
– If voltage measured is battery voltage, go to step B.
– If voltage measured is zero, repair the circuit from the GAGES fuse to the solenoid and re-check the
solenoid operation.
B. Remove the injection pump governor cover and do the following things:
– Connect a jumper wire from the HPCA solenoid to the vehicle battery negative terminal.
– Momentarily connect and disconnect a jumper wire from the HPCA solenoid to the vehicle battery
positive terminal.
– Observe the solenoid action:
• If it operates, check the housing pressure regulator and fuel return system for a restriction.
• If it does not operate, go to step C.
C. Measure the resistance between the HPCA solenoid frame and the injection pump governor cover:
– If the resistance measured is less that 0.5 ohm, replace the solenoid, install the governor cover and re
check the solenoid operation.
– If the resistance measured is more than 0.5 ohm, repair it, install the governor cover and re-check the
solenoid operation (refer to Figure 7-51 on page 7-54).
5. Move the ignition switch to the OFF position.
6. Install the electrical connector for the HPCA solenoid from the injection pump.
7. Remove the diesel injection timing meter, if used.
