fuel problem ford f-150 run's on back tank will run on back tank kinda poor but it will not start on front tank if under 1/2 tank and spits and sputters

fuel problem ford f-150 run’s on back tank will run on back tank kinda poor but it will not start on front tank if under 1/2 tank and spits and sputters

fuel problem ford f-150 run's on back tank will run on back tank kinda poor but it will not start on front tank if under 1/2 tank and spits and sputters if you try going over 55 and the front tank keeps getting gas in it even tho only putting gas in the back tank????

You weren’t specific, but this is common to the 80’s – 90’s trucks with dual tanks. The problem most often stems from failure of  the switching mechanism between tanks, or the in-tank pumps. Different years have different designs, which are troubleshot differently. Earlier trucks often have a frame-mounted switching valve, while later trucks use the in-tank pump/module itself to pump from the selected tank. Your tank-filling symptoms sound more like the later (after 1990) models, which means I would recommend replacing the pump/module in the tank that is filling up. A broken check valve in the module may be allowing fuel from the rear tank to enter the front tank, instead of directing its full pressure to the manifold fuel rail. This can cause the sputtering symptom, due to reduced fuel pressure. There is also the real possibility that if you are unable to (or just don’t) pump from the front tank, that the additional fuel coming from the rear tank will eventually fill the front tank to the point of  overflow or leakage.

Tom Dayton
JS Auto Supply

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