Yukon 4WD V8-6.5L DSL Turbo VIN S (1997)
Fuel Inlet & Return Lines: Testing and Inspection
The diagnosis of fuel odor may be a condition of a leaking fuel feed, or return pipe or hose. Fuel pipes that are pinched, plugged, or mis-routed may
cause restricted fuel delivery. 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.
3. Connect a vacuum pump with a gauge to the hose.
4. Apply vacuum to the return line.
5. Observe the gauge reading.
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If the vacuum does not build and hold, Go to Step 4.
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If the vacuum builds and holds, repair the return line restriction.
6. Connect the fuel return line at the injection pump and the fuel sender.
7. Clean any fuel spillage.
8. Run the engine to check for fuel leakage.
