Hey all,
Got an issue with my 1996 F250 4x4 SuperCab 5.8L. I have twin tanks. The rear one has no issues whatsoever. The front one...when it's full of fuel it will run fine for a bit and then will start to act like the truck is suddenly weighed down with an anchor. Pressing the accelerator to the floor actually makes the issue worse. Wildly varying the accelerator position seems to get me through it, but that is kind of a pain. The more fuel that gets used the better the problem is, when the tank is almost empty it seems to work fine like 90% of the time, the other 10% is like the symptoms above.

I suspect it's the fuel pump (or fuel delivery module as some call it). Does that seem right? Just thought I'd ask before I go through the trouble of dropping the tank, changing the FDM and putting the tank back in.

Thanks for the help.

 

You could put a fuel pressure gauge on it and see if the pump varies pressure.
More than likely it's weak.

 

How would I do that? Can that be done while driving the truck? It only seems to be an issue when driving the truck.

 

Ummm, yeah. Need to drive it to see if pressure goes down under load.
If you can't find a fuel pressure gauge, an oil pressure gauge will work if you have a 1/16 fitting.

 

Hate to be the bearer of bad news, but I just replaced my rear pump, doing the same thing. And wow, does Motorcraft really think alot of theirs! Wish I knew which other brand pumps were as good.

 

Yeah sounds like the pump's done. When you hit the gas it can't keep up with demand. Had one do this exact same thing as well.

 

Thanks guys (and gals). I appreciate it. I just wanted to know if what I suspected was probably true, before I went ahead and went through all the work to get the tank out, replace the unit, and reinstall the tank. Thanks!

 

My front pump was failing and did the same thing. I purchased a fuel pressure gauge from harbor freight (bout $20) and tested it. I was getting 45 psi at idle and it dropped even lower under a load. Normal for my engine (4.9) should be about 55-60. I'm pretty sure that the v8 fuel pressure is within 5 pounds of my straight 6 since they have similar displacements.

After troubleshooting, if you determine that your fuel pump is failing, You also will need to investigate what size and kind of tank you have so that you have. There are a couple diferent options for fuel pumps.

 

Almost all the fuel pumps on rockauto.com looked the same, so I went ahead and ordered one. We'll see!

 

At least Rock Auto carries the correct Ford Motorcraft fuel pump.

 

I bought the AIRTEX Part # E2059MN. Looked just like the rest, is one of their "favorite" parts and had a video on how to install.

 

A couple of other questions for you fine folks!

1) I'm very handy...approximately how long does it take to remove the fuel tank?
2) Can the truck be driven without the front fuel tank in the event I cannot get it all done in one afternoon? (as in can it be driven without spewing gas everywhere if I only have the switch to the rear tank/pump?)

 

Removing the front tank was not hard in my opinion. First thing was to transfer the fuel out of the tank. I used a 5 dollar hand pump.
-next I put 2 jack stands under the fuel tank And a jack to control the weight.
-disconnect the 2 straps (just a bolt and nut on one end of the strap)
- the I lowered my tank a few inches to gain access the fuel lines and the fuel neck. Disconnect them and unplug the fuel pump.
-then drop the tank the rest of the way down to the ground
-use a punch (I used plastic scraper so as not to create sparks), with the punch hammer the ring that secures the pump housing to the tanks ( should rotate the ring less than 1/4 of a turn
-remove the ring and pull the pump assy out of the tank.
-look for the float, fuel strainer, and oring if they fall off

Installation is in the reverse.

A few notes, I replaced my entire fuel pump assembly. If you replace only the fuel pump itself you will have to unhook the pump from the hanger and wire the new one in place.
-also my new pump used the new style connector and I had to splice in a new harness connector. Not hard but it added a few more minutes to the install.

All together it took me about 2 hours using basic tools from my garage.


-----also I kept a water hose near by and I soaked my driveway down and kept it wet while dropping the tank (just to be safe)



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As far as driving with the tank removed. It's not as simple as just unhooking it and driving with the selector on the other tank. There are some changes that have to be made and I can't remember off the top of my head what that process is.
I know that the tanks do cross feed with each other and the check valves are on the fuel pump assembly, so with the fuel pump removed the open line will dump fuel due to pressure from the other pump.

 

Ignore this. I misread a previous post.

 

Well...got it changed yesterday....it was indeed the pump. However now it leaks slightly at the junction of the fuel pump hanger and the tank flange. I had to reuse the original seal because none of the new ones would fit. I did thoroughly clean it, but i wonder if I didn't run the locking ring around far enough. Do you guys think that I can crawl under the truck and tap the ring around further or am I going to have to take it back out and replace the seal?