Hey everyone, my 95 F250 5.8 has a rear fuel pump issue, the one I replaced failed, no gas to the engine what so ever, the tank also had a hole in it. So I had a 92 F250 5.8 on blocks for parts (light duty if it matters) and I pulled the tank and pump together, sending unit works fine, pump pumps, but the harness's don't match so I spliced into it. So the issue is, it won't let the engine rev about 3000 rpm when sitting and I rev, and when driving won't accept more than 1/8th throttle, on flat ground I can maintain a speed of 110 kmh or 70mph with out cruise control on, with cruise control it dies and coughs and will just fight itself, just like when I try and accelerate on the rear tank... What stumps me is the fact that my 92 (parts truck) ran and drove completly fine on both tanks before I took the front suspension out of it and blocked it... What's going on here? What could I do to try and fix this? Could it be possible the pump sucked up some dirt? And I'm considering throwing a gallon of diesel into 17 gallons of gas to clear it out, would this be okay?

 

I would change the filter first and if you still have the problem you need to put a fuel pressure gauge on the fuel rail and tape it to the windshield so you can see it.
The fuel pressure should be 30-34psi at idle and go to 40psi under WOT on a hill or accelerating at a high rate.

 

Alright will do! Thanks! But it seems as though I need to drop the front tank to replace the filter... And I have no issues on my front tank so I'm doubtful about it being the filter, I've tried before and had no luck with the filter, and left it as my truck ran fine on my front tank

 

Yes if it runs fine on the front tank, sorry I did see that you said that.
I would guess that the sock in the tank is plugged up then.

 

Is there anything I can throw in the tank to clean off the sock? I really don't feel like dropping the tank again...

 

I do not know of anything other than cleaning the tank and replacing the sock filter strainer.
But I like to take the bed off other than dropping the tank as I find it much easier then fighting with getting the tank dropped. But if you have the lift in your avatar photo then dropping might be better.

 

Yeah... Sadly I don't have that hoist, I think it's also time to replace the tank itself aswell ...

 

Sorry to bring back an old thread! I began my "sixlitre" tune up with 9mm Ford Racing wires, MSD Cap and rotor, and performance world 48,000 volt coil. I left my plugs at 0.045 and my truck ran amazing! On my rear tank I could go as much as 3/8th throttle and maintain 110 kmh (70 mph). I pulled my plugs today to regap them, they were running VERY LEAN after the wires, cap, rotor, and coil without gapping them. My gapping tool didn't have 0.055 so I took a shot in the dark and went for 0.060. My truck runs nice, it idles great, but it seems either it doesn't pull as hard, or it pulls just as hard but starting at a lower RPM. ON MY REAR TANK, I can no longer touch the throttle, the engine just seems to die, which got me thinking, I'm getting awesome fuel economy on my front tank (600km to a tank) and aweful economy on the rear (200km to a tank). When I fill up, my rear is empty, and I think my front is empty, but it normally takes $15 or so... HERE IS MY QUESTION!!!!

Is the rear tank throwing too much fuel into the engine?? And if it's lack of fuel, either way, the rear tank fuel is ending up in the Front tank?

Tomorrow I will pull my plugs and gap them to 0.050 and also see how lean/rich my truck is running since gapping them to 0.060. For the record, my plugs are Bosch Platnium plugs with about 6300 km on them.

 

No that is not possible.
You have a lack of fuel pressure getting to the engine.
You have a bad front fuel delivery module in the front tank.
Sounds like the back one is OK.
That will not help and it has been reported that the Bosch Platnium plugs do not run very well in our trucks.
The MSD parts will not make it run any better and sometimes not as well than new Motorcraft parts. New AWSF-32C Motorcraft plugs should be gaped to .042 - .046.