1988 F150 Lariat EFI Rear Fuel Tank Feeding Front Fuel Tank Problem


Asked by Aug 20, 2015 at 02:32 AM about the 1988 Ford F-150 XLT Standard Cab LB

Question type: Maintenance & Repair

1988 F150 Rear Fuel Tank Feeding Front Fuel Tank Problem.  When switching from front to rear tank.  I noticed gas dripping from my front tank.  I took off the cap and gas gushed out.  At first I thought I overfilled it, but when it happened the second time I knew something was wrong.  My front tank also showed full again after driving over a hundred miles. Please advise.  Thanks in advance.

3 Answers


No familiar with the system of a truck with your vintage, but it sounds like something is pressuring the front tank. Check to determine if when you switch to the rear tank that the pump for the front tank is not still running. Also, from your post it sounds like the return line on the gas tanks is sending the fuel to the front tank only.

1 of 1 people found this helpful.

There is a tank switching valve is sticking. The high pressure pump is pumping fuel from full tank to empty tank. You need to service the switching valve. (or replace)

3 of 3 people found this helpful.
Best Answer Mark helpful

Thank you for your response. I did some more research and ended up replacing the tank function tank switching valve; Dual Function Reservoir (DFR). Problem solved, the front pump stopped whining and rear tank stop filling the front tank and so far no intermittent more engine light and shut off. I found my most helpful info form this post, http://home.budget.net/~klricks/F150/Dual_Tank_Selector.html Although when you keep digging you will find more. Most of which where spot on.

4 of 4 people found this helpful.

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