Fuel System Air Leak Check

1. Install a transparent hose between the filter outlet and the injection pump inlet.
2. Start and idle the engine, observing the fuel for air bubbles.
^ If air bubbles are not present, stop the engine and Go to Step 7.
^ If air bubbles are present, stop the engine and Go to Step 3.
3. 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.
^ Apply vacuum to the fuel pipe and 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.
4. Check the fuel sender for air leakage.
^ Remove the fuel tank.
^ Remove the fuel sender from the fuel tank.
^ Remove the strainer and 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 (fuel inlet side of 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.
5. Start and run the engine.
6. Observe the fuel for air bubbles.
^ If 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 7.
7. Remove the transparent hose and connect the hose of the filter outlet to the injection pump inlet fitting.
8. Disconnect the return hose at the injection pump.
9. Install a transparent hose between the injection pump and the hose of the return line.
10. Start and run the engine.
11. Observe the fuel for air bubbles.

IMPORTANT: It is normal to see small amounts of bubbles during snap acceleration.
^ If air bubbles are present, replace the injection pump. Refer to Fuel Injection Pump Replacement.
^ If air bubbles are not present, Go to Step 12.

12. Stop the engine.
13. Remove the transparent hose and attach the fuel return hose at the injection pump.
14. Clean any fuel spillage.
15. Run the engine to check for fuel leakage.