Testing the fuel cap

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Remove fuel cap.

Fig 1: Fuel Cap Receiver Connect To Hose

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Connect fuel cap receiver (arrow) to hose.
Screw fuel cap tightly to cap receiver.
Turn control valve to "Test" pressurizing cap.
Turn valve to "Hold".

Watch pressure gauge for drop in pressure from 14 inches H ₂ O.

If no pressure drop is indicated:

Proceed to checking Leak Detection Pump (LDP) V144 for internal leaks.

If pressure drop is indicated:

Replace fuel cap and re-test.
Proceed to Checking Leak Detection Pump (LDP) V144 for internal leaks.