Hello I'm a new user to this sight. I live in Arlington Texas. Anyways I have a 1994 ford f-150 with the straight six motor, dual tanks. I was wondering if there is anybody out there that could tell me how to plug off the front tank and just use the rear tank due to the fuel pump on the front tank is bad. Also when I put gas in my back tank somehow it transfers to the front tank. WHAT COULD BE THE PROBLEM DOES ANYONE KNOW.........

 

Welcome to

You certainly came to the right place for this problem. It's a very common issue on these era of trucks. I don't know the exact details of what's happening, but if you do an advanced search on this section of the forum (that is, the 87-96 section) for "FDM cross over problem" you will find plenty of threads on the subject.

Good luck and keep us updated!

 

You have a bad valve on your front tank fuel delivery module (FDM). I have the same problem on my '96 F150. An OEM FDM will set you back about $450 (including the pump). In the spring, I'm getting the FDM and a new front tank w/straps and hardware and will replace them when it warms up a bit. I'm getting an entire FDM because the pump is bad, the sending unit is bad, and the valve is bad on the front FDM. If everything else is working for you (your front tank fuel gauge is good, and you're getting enough fuel to the engine from the front tank) maybe you can get away with keeping the pump and just buying a sending unit.

 

No reason to go OEM, in my opinion. And as far as I know, the check valve that failed on the OP's truck is inside the pump. No reason to replace the entire unit. (I could be wrong on that one)

Just the pump:
Airtex Electric Fuel Pump E2059MN: Find best Fuel Pump at Advance Auto Parts


You and I have the same truck, and I did this repair about 6 months ago, and it's really not a bad job. Didn't even have to jack up the frame.

FWIW, a mechanic friend of mine said the easy way was to pull the bed, and do both tanks at the same time. Thought it sounded stupid, but then my rear pump started having that check valve problem just recently. I'll be replacing it when the weather warms up a bit.

Also, if you do have the check valve problem, it's important to replace it, especially if the front pump isn't pumping gas anymore. It's my understanding that complete check valve failure could lower the fuel pressure enough to where the truck won't run even on the good pump.

 

You know, I was told the best way to go about it was to pull the bed as well. It's only 6 bolts. Most have had to cut them off though, but no biggie. i thought if I'm going to pull the bed to do the front, why not do the rear tank as well, since no doubt it is near the end of it
s life as well. I usually do OEM parts for things like this because, well, the first ones lasted 17+ years, and I don't want to buy after market and do it again in 5 years. Doing both new tanks with OEM FDM's would cost over $1000 though. At least I won't have to worry about them anymore!!!

 

Totally agree with you about the OEM Parts. But in this case, I had heard good recommendations about the Airtex pumps, and the price made the decision for me. I can't speak for the other ones.

 

If you at all handy with a hack saw and angle grinder you can fabricate plugs for the fuel lines. You will need to find a couple engine studs like those in the pic below, cut the threads off 1 end and round over the edge, and then grind the nut part of the stud so that it can be retained by the factory fuel line retainer clips. The item on the top left of the pic is an inline check valve that was part of TSB to address the tank crossflow problem and these plugs won't insert into that. Also note that you need different sizes studs for the send and return lines.

 

I know there was a recall on a lot of these trucks. We used to have to pull the bed and put these check valves inline with the in an out

 

Not to be a dick, but you gotta do a search.
You need to replace the fdm, or fuel delivery module. Not just the pump if the fuel is going from one tank to the other.
Lots of reading on this subject.

Search for
Fuel crossover
Fuel transfer
Fdm

 

The cross-flow fuel issue recall was only for '89 - '93 F-series. The OP has a 1994:


F150

FUEL SYSTEM, GASOLINE

Recall number: 01I008000
Recall date: 07/19/2001
Problem Summary:

THIS IS NOT A SAFETY RECALL IN ACCORDANCE WITH THE SAFETY ACT. HOWEVER, IT IS DEEMED A SAFETY IMPROVEMENT CAMPAIGN BY THE AGENCY. VEHICLE DESCRIPTION: 1990-1993 FORD F-SERIES VEHICLES EQUIPPED WITH DUAL FUEL TANKS AND 4.9, 5.0,5.8, OR 7.5 LITER GASOLINE FUELED ENGINES. SOME VEHICLES CAN EXPERIENCE A CROSS TANK FUEL FLOW CONDITION DUE TO A DAMAGED CHECK VALVE IN THE FUEL PUMP/SENDER ASSEMBLY. FUEL MAY BE SUPPLIED FROM ONE TANK AND SOME OR ALL OF THE UNUSED FUEL MAY BE RETURNED TO THE OTHER TANK.
Consequence:

SHOULD THIS OCCUR, THE CAPACITY OF THE RECEIVING TANK MAY BE EXCEEDED AND FUEL MAY OVERFLOW FROM THE FILLER CAP.
Corrective Action:

FORD IS EXTENDING THE WARRANTY FOR POTENTIAL FUEL CROSS-FLOW TO 12 YEARS OF SERVICE OR 150,000 MILES FROM THE VEHICLE'S WARRANTY START DATE, WHICHEVER OCCURS FIRST. THIS COVER WILL AUTOMATICALLY TRANSFER TO SUBSEQUENT OWNERS AT NO CHARGE. IF A VEHICLE ALREADY HAS MORE THAN 150,000 MILES, THIS OVERAGE WILL LAST UNTIL DECEMBER 31, 2001. IF THE VEHICLE IS EXPERIENCING A FUEL CROSS-FLOW CONDITION, DEALERS WILL REPAIR THE CONDITION FREE OF CHARGE.
The manufacturer first notified owners of this recall on 07/09/2001.
This recall affects vehicles manufactured between 07/22/1989 and 08/24/1993.
<HR>

 

When you replace the FDM and the pump/sender in these tanks, can you reuse the original fuel pump hangars ???

 

Fuel pump hanger?
All you need to replace, unless you break it or it's really rusted, is the tank straps or the retainer ring holding the sending unit assy into the tank, is the fdm itself. The rest is typically reuseable.