Any restriction in the fuel return system could greatly effect driveability. If other diagnosis indicates or the fuel return system is suspected of being restricted, it should be tested.

1. Disconnect the hose of the fuel return line at the fuel sender.
2. Disconnect the hose of the fuel return line at the injection pump, and connect a vacuum pump with gauge to the hose.
3. Apply vacuum to the return line and observe the gage reading

•	If vacuum does not build and hold, Go to Step 4.

•	If vacuum builds and holds, repair the return line restriction.

4. Connect the fuel return line at the injection pump and fuel sender.
5. Clean any fuel spillage.
6. Run the engine to check for fuel leakage.