Hey,
I just bought a 1990 5.0 302. It was sitting in some guys yard for at least 4 years, so I've had to change out a few things. I changed the rear fuel pump, and pinched off the lines to the front tank until I get a new tank (the old one was too rusted to use). The truck started right up and ran fine for awhile, but now it's starting to have issues. I'll explain the symptoms and hopefully someone will be able to help me out.
First, it would only bog down when I was going up a hill in a high gear. I'd press the gas in order to get up the hill without downshifting, and the engine would act like it wasn't getting any gas. First thing I did was fill the tank up, and it seemed to run fine. I figured I put the fuel pump in wrong.
Then it started happening with a full tank, same symptoms.
Now it's happening all the time, even under almost no load.
I've checked the fuel filter, it's fine.
The codes read that the TPS is bad, but I tried to check it and I wasn't sure which wire was which. So, I just unplugged it and the truck ran great for about 10 miles. Then, the same thing started happening.
Could the TPS cause a problem like this? A friend of mine said it might be the catalytic converter, or maybe the auxiliary pump.
Any help is greatly appreciated.

-Kolby Matson-

 

i had the same problem on a 97 it happend to be a plug wire they all looked like new but one of the wires broke inside try it its a cheap fix if the truck is that old it probably wouldnt hurt to throw new plug wires on it anyway

 

I'd try the plugs, wires, cap, and rotor - that should get the spark back in order. Maybe run some seafoam through the intake, oil, and gas tank too.

I have to ask - please give me details on how you 'pinched off' the fuel lines to the front tank. I have some front tank issues too, and would love to figure out how to get around it until I can actually fix it.

 

Pinching the plastic lines is not a good idea.

 

It wasn't too hard...I tried just bending them back and ziptying them, but it was still leaking when the fuel lines were under pressure. So, I had to pull the protective tubing back (covers the actual fuel lines, starts right at the fuel sending unit and goes back about 2 feet to the frame). Once I pulled that back, the lines pinched right off and I ziptied them again, works great. I figured worst case scenario I change a couple feet of broken fuel line. I had to do it because I have to change my front tank, but I need the truck until my tank comes in. I just hope this doesn't have anything to do with my current problem...if for some reason the excess fuel isn't being directed back into the tank?? I read somewhere something about return fuel lines...but I think the rear and front returns are on the same line, so it should just return to the rear if that's the only tank I'm using...any thoughts?

 

Each tank has a valve that keeps the fuel from pumping into it when it isn't selected. If you were running with the rear tank and the fuel was going back to the front tank then the front tank valve is bad. The valve can't be purchased separately, it comes with the fuel pump assembly.