GM 6.5L V8 – Fuel System – Fuel Injection Pump Advance Mechanism Check

1. Bring the engine to operating temperature.
2. If available, install a diesel injection timing meter (J 33300).
3. Remove the intake manifold upper cover (sound insulator).
4. Start and run the engine.
5. While the engine is running at 2,000 rpm, use a long screwdriver to press the bottom of the rocker lever for the injection pump light load advance mechanism inward (see Figure 7-75).
6. As the rocker lever is pressed inward, observe a change in engine speed:
• If engine speed drops (injection timing retards), go to step 7.
• If engine speed does not drop, replace the injection pump and re-check the advance piston operation.
7. Stop the engine.
8. Install the intake manifold upper cover (sound insulator).
9. Remove the diesel injection timing meter, if used.


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