Please Help
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New User
Joined: Nov 2004
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Please Help
I have a 96 F350 crew 4X4 with 150,000 miles my problem is as follows about 6 months ago truck started to slowly get worse to the point it would barely idle using the front tank. I switched to back tank and it ran fine with the exception of fuel somehow seeping into front tank causing it to over flow. I would siphon some out and it would slowly re fill. well now truck with not run while using back tank either it will idle but is un driveable seems like it is not getting enough fuel. again this problem slowly came on. I have no idea where to start or what it might be with out just starting to change parts. This has been a great truck only major work has been to replace the tranny a year ago. Is this a pump prob., reg prob, switch prob? please help I use this truck every day to get to work thanks again.
Fleet Mechanic
Joined: Jul 2004
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From: va
Bad fuel selector valve
This was my problem also on my 87, 4.9. If fuel is being pumped into the other fuel tank then its your fuel selector valve. Big problem with the 87,88,89, all had the same part. Its located under the drivers seat, attached to the frame under the truck with two mm bolts. Its got 4 fuel lines in back and two fuel lines in front. There was a recall for 1989's, to see more about this at www.alldata.com look on the left for T.S.B.'s and then choose 1989 ford at the bottom of the page and then choose any engine size. Type in the recall number at www.google.com to find out more. Try the Advance Search, and type in fuel Selector Valve. You can only get this part at Ford for about 53.00, at a small ford dealer. You may also have a bad in tank fuel pump but wait and see.
EDIT:
oops With your newer truck its a different setup. On the 1992 Recall ( fuel cross flow problem) http://www.alldata.com/TSB/20/92202125.htm it needed a cross check valve added to a fuel line.The shuttle valve in the FDM or in tank fuel pump is probably stuck open and can't be replaced. Not sure if they can add this to yours or you willneed a new in tank fuel pump.
EDIT:
oops With your newer truck its a different setup. On the 1992 Recall ( fuel cross flow problem) http://www.alldata.com/TSB/20/92202125.htm it needed a cross check valve added to a fuel line.The shuttle valve in the FDM or in tank fuel pump is probably stuck open and can't be replaced. Not sure if they can add this to yours or you willneed a new in tank fuel pump.
Last edited by mike L; Jan 3, 2005 at 11:22 PM.
Elder User
Joined: Sep 2004
Posts: 941
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Ford realized that the selector valve didn't work. They changed the fuel system in later years to a module that included a high-pressure pump, shuttle valve, and check valve in each tank. Your 1996 would be one of those "later years". The supply and return lines connect in parallel. The check-valve prevents backflow from the "live" pump back into the tank. The shuttle valve ensures that the fuel return line is only opened to a tank when the pump in that tank is producing pressure. There is no selector valve.
My guess is that the failing front pump is allowing pressure built by the rear pump to be bled off into the front tank. This causes the front tank to overflow and reduces the effective output of the rear pump, by creating what amounts to a big leak.
My guess is that the failing front pump is allowing pressure built by the rear pump to be bled off into the front tank. This causes the front tank to overflow and reduces the effective output of the rear pump, by creating what amounts to a big leak.
Senior User
Joined: Sep 2004
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From: SC lowcountry
Don't know about F350 but F150 95 Does not have fuel selector valve - it uses internal check valves in each tank pump unit to isolate front and rear pressure. Best bet is to check fuel pressure on rail in engine compartment and check codes in computer. A plugged fuel filter could be a major problem - it is probably in line on frame rail under driver side. Fuel pressure would show that also. Good luck!
