Got a 1996 F-150, 5.8L V8, optional fuel tank with 180k miles on it. Recently, our front fuel pump has been in the process of dying. The truck starts real hard and if it's on an incline it doesn't start at all. Solution? Don't use the front, the rear tank works just fine. Haven't spent the 150 or so to get a new pump.

My sister has a 2004 Dodge which means my truck is more reliable and her SUV died so she's been borrowing my spare vehicle, the F-150. I told her not to put fuel in the front, use the rear tank. She kept insisting that she wasn't but lo and behold, there was always gas in the front tank. I thought she couldn't figure out there were two gap caps or something. Then I realized she really wasn't using the front tank because the front tank is actually overflowing and leaking gas everywhere. It appears that when she's running on the rear it pumps fuel to the front tank.

I've worked on cars before, usually not my truck. (What can I say, the thing never breaks). Will replacing the front fuel pump fix the problem? I'm thinking maybe the back pressure valve or something is stuck open so any gas getting pumped ends up in the front tank? I've found a few threads on this problem but none are my year and most go a bit over my head as the most work I've done on the fuel system is replacing a filter or three.

Is the check valve a separate component or is a part of the fuel pump? I know earlier years had a recall but there are a lot of consumer complaints for my model year, Ford just never acknowledged it.

I'm thinking of talking to the guys at the local Ford dealership but we've never taken it there so I'm not really sure if they're shady or relatively legit. Also, if anyone has the right part number for what needs to be replaced it'd be helpful. I have the repair manual for my truck so I can do the work in a weekend just sort of at a loss for where to start looking for parts.

 

You need to replace the pump in the front tank. On that truck there is no switching valve. The pumps have check valves that stick open and cause the fuel transfer. The only way to stop it from happening is to replace the pump.

 

Didn't feel like dropping a fuel tank so I took it to Big Valley Ford (Stockton, CA) and they tried to tell me I was missing a check valve between the two tanks. Yes, a missing check valve between the two tanks was causing fuel to stop at the front tank. Nice. No, I'm not an idiot nor was I born yesterday. I've also own the truck for 12 years and it only did it recently. Any major repair (none, for the record) has been done when I owned it. It's had oil changes and brake pads and nothing else. Thing runs great. Don't try and tell me somebody must've removed a part off the fuel line because I replaced the fuel filters myself. Nobody has worked on the fuel system.

Not an idiot here. It's a sixteen year old truck. Why was it running for 16 years with a missing part, explain that. Plus they kept insisting the front pump was fine. It can't start on a slight incline in my driveway off the front tank, have to start on the rear and switch to the front. That says 'dying'.

End result? 500 for a new check valve to be installed between the tanks (still not sure how it's supposed to stop fuel going into the front from the rear when the fuel returns if it's behind the front tank...) and bump the bill to 800 total in order to replace the front fuel pump even if they didn't think it was necessary.

I said that's nice. Here's the 130 or so for the BS diagnoses. Thanks but no thanks.

 

You do not need a check valve in the fuel lines. As you know it never had one.
Each FDM (Fuel Delivery Module) has a check valve on its pressure side. It also has a return shuttle valve on the return side. Either one could be bad on the front tanks FDM.
Your truck has two FDM.

Your fuel system:


The Fuel Delivery Assembly below consists of the fuel pump inside a reservoir that is attached to the pump and sender assembly. In a two tank system there is one assembly per tank. The sender Module handles the switching of the fuel through internal valves. To service the assembly, replace it.



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