I HAVE A 1990 F-150 THAT MAKES A NOISE AFTER THE TRUCK HAS BEEN TURNED OFF. PREVIOUSLY THIS NOISE WAS ONLY HEARD FOR ABOUT 5 SECONDS WHEN STARTING, JUST BEFORE ENGAGING THE KEY FULLY. IT IS COMING FROM THE AREA OF THE FUEL TANKS AND CHANGES SLIGHTLY WHEN I SWITCH FROM THE FRONT TO REAR TANK. I USUALLY HAVE TO DISCONNECT THE BATTERY TO AVOID A JUMPSTART. ANY IDEAS? THANKS.

 

Do you have an electic fuel pump and or transfer pump for dual tanks. Sounds like you could have something running when it should not be. Get out your test light and volt meter and start checking with the key in the start position but engine not running.

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97 F-150, 2WD, Reg Cab,Flareside,Dk Toreador Red, Windsor 4.6, Magnecor 8.5mm wires, Bosch Plat +4s, 3.55 LS, EGR Bug Deflector, ******* Bed Cover, Bed Liner, XL Full Length Running Boards, Air Aid Kit, Gibson Single Out Cat Back, Superchips, TransGo Shift Kit, Hellwig Rear Sway Bar, Hellwig 2500# Overload Springs