Fuel System Air Leak Checks

1. Install a transparent hose between the filter outlet and the injection pump inlet.
2. Start the engine.
3. Allow the engine to idle at the normal operating temperature.
4. Check the fuel for air bubbles.

- If there are no air bubbles present, stop the engine and Go to Step 6.
- If there are air bubbles present, stop the engine and Go to Step 3.

5. Check the lift pump suction line for air leakage.

- Disconnect the fuel pipe from the fuel sender.
- Plug the fuel pipe.
- Disconnect the fuel pipe from the lift pump.
- Install a hand held vacuum pump with a gauge to the fuel pipe.
- Apply vacuum to the fuel pipe.
- Observe the gauge reading.

- If the vacuum does not drop, connect the fuel pipe and Go to Step 4.
- If the vacuum drops, repair the air leak in the suction line and install the suction line pipe and the hose.

6. Check the fuel sender for air leakage.

- Remove the fuel tank.
- Remove the fuel sender from the fuel tank.
- Remove the strainer from the fuel sender.
- Plug the bottom end of the pickup tube.
- Apply a vacuum to the upper end of the pickup tube.
- Observe the gauge reading.

- If the vacuum does not drop (if the fuel inlet side of the sender is OK), install the fuel sender and the fuel tank.
- If the vacuum drops, replace the fuel sender, install the fuel tank, connect the fuel pipe and Go to Step 5.

7. Start the engine.
8. Allow the engine to idle at the normal operating temperature.
9. Observe the fuel for air bubbles.

- If any air bubbles are present, stop the engine and recheck Steps 3 and 4.
- If air bubbles are not present, stop the engine and Go to Step 6.

10. Remove the transparent hose.
11. Connect the hose of the filter outlet to the injection pump inlet fitting.
12. Disconnect the return hose at the injection pump.
13. Connect a transparent hose between the injection pump and the hose of the return line.
14. Start the engine.
15. Allow the engine to run.
16. Observe the fuel for air bubbles.

NOTE: Small amounts of bubbles during snap acceleration is normal.

- If any air bubbles are present, replace the injection pump. Refer to Fuel Injection Pump. Service and Repair
- If th6rn are no air bubbles present, Go to Step 10.

17. Stop the engine.
16. Remove the transparent hose.
19. Connect the fuel return hose at the injection pump.
20. Clean any fuel spillage which may be present.
21. Run the engine to check for any fuel leakage.