I have an 88 f350 351w single tank.
Here's what happened...
I ran out of gas. I put 5 gallons in it. On my way home, it started acting like it was running out of gas again. I stopped and filled it, but still under a load (accelerating up hill) it would sputter and feel like it was running out of gas again.
Thinking it might have been water in the fuel, I loaded it with dry gas. Didn't help.
The problem has gotten worse, to the point that at any time If I give it more than a quarter throttle it sputters and loses power.
I then thought it was a spark problem... I cleaned the cap and rotor and checked to make sure all the plug wires were connected on both ends.
I changed the fuel filter. I dropped the tank. The pump in the tank is pumping and the high pressure is pumping. The pickup sock is clean, as is the inside of the tank.
Even in neutral, if I floor the pedal, it pops through the intake and runs up a bit (maybe 1000 rpms) then drops and pops and over and over.
I am going to put the pump back and put the tank back in...
What should be my next plan of attack??? Spark plugs? I'm out of ideas.
Any help would be greatly appreciated.

 

I would pull a few random plugs and check thier color. Go to a parts store and rent or buy a fuel pressure tester.KInow what your fuel pressure is before you just go throwing parts at it.

 

That truck has that resovoir/switching valve thing on the frame that could be acting up and causing pressure porblems, so get a gauge and test fuel pressure so you know if there is a problem with the fuel system or not. It should make and hold 40-45psi at the motor at all engine speeds and loads when vacuum is removed from the regulator. If all that checks out pull the codes and go from there.

 

They have the res/switching valve on single tank systems?
It seems like its getting pressure, but not volume.
Thanks,
I really appreciate the help!

 

I think you may have a bad TPS.
You need to run the EEC Self-Test and see what codes you get.

 

That is very possible.
I'm not sure if this changes anything, but if I let it idle for a few seconds and then give it gas, I get one quick burst of power and then it starts stumbling and popping again. That's what made me think it was a restriction in fuel.

 

You say you have a single tank but did this truck when new have two tanks and if so does it still have the two tank selector valve on the frame?

If so Paul may be right in post #3 above in this thread.

If not you should still have a single tank reservoir in place of the two tank reservoir/valve. Take the cap off the bottom of the reservoir and see if it is not full of junk and it may also have a fuel filter inside. I know only the 1985-86 trucks had the filter inside of the reservoir but maybe someone may have changed it out with an 1985-86.
If you take the cap off the bottom the "O" ring may get out of shape and to replace it you may have to buy a filter for a 1986 Bronco II and throw the filter away to get the "O" ring.

Single tank reservoir:


Two tank reservoir:


/

 

Thanks for all the help. I will post back with my results.