Dual tank problem
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More Turbo
Joined: Oct 2004
Posts: 621
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From: Marana, AZ
Dual tank problem
I have 1994 F-150 2wd with a 4.9L EFI and dual tanks.My rear tank pump went out years ago, so I have only been using the front tank. Well it went out too, and I replaced the pump in the front tank and everything seemed to work well. Come to find out the front tank is pumping fuel into the rear tank now. Not always though, its kind of intermitten. Any ideas?
Elder User
Joined: Dec 2002
Posts: 559
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From: South Carolina
The Fuel Management Unit is faulty on the rear tank. It has a broken check valve that's letting return fuel leak into the rear tank. The Ford recall is time or mileage dependent, I think. It may not be active anymore, but you can check by calling a Ford Service department with your VIN #.
Senior User
Joined: Jul 2005
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I have been going around and around with this for some time with my '93. I had the recall done that had to do with the fuel regulator, where it could put too much pressure on the check valves and evidently ruin them. Come to find out the tanks are cross flowing, so they DID get ruined. I was trying to see if another recall would have applied, but they said no at ford. I don't know if I have the time and energy to try and convince them that what they already replaced probably was bad, and caused my cross flow problem. In any event, I got a new aftermarket pump, and the check valves are built into it. You should be able to do the same if Ford doesn't give you any satisfaction.
Elder User
Joined: Dec 2002
Posts: 559
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From: South Carolina
When you buy the aftermarket replacement for the fuel pump, it comes as the complete "fuel management unit" for that tank, including the check valve that is causing your problem. On mine, it had the Ford part numbers scratched off - an OE part in an aftermarket box. This happens sometimes when the aftermarket can't build a replacement cheaper than they can buy it.
Junior User
Joined: Sep 2003
Posts: 98
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From: East Coast
Think I might know this one if it's the same as my 88'. There is a canister located 2' behind your high pressure fuel pump inside the drivers' side frame rail. It's the size of a small oil filter. This valve is mechanical and is supposed to prevent your problem. It's stuck. You can either buy a new one for the low low price of $106=tax or take it apart and clean it up. I can get you a part number if you need it. Not sure if it applies to your year.
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Joined: Oct 2004
Posts: 621
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From: Marana, AZ
Thanks guys for the info!
I guess I will be doing this grueling task all over again. Those damn fuel lines are a pain in the @!! Just found out the fuel pump went out in my 91 Bronco as well. Go figure!
I guess I will be doing this grueling task all over again. Those damn fuel lines are a pain in the @!! Just found out the fuel pump went out in my 91 Bronco as well. Go figure!
