I have a 1991 Ford F150
4.9L Straight 6
Auto tranny w/ OD
Dual Tanks

Will run on the rear tank. Starts and runs.
If I switch over to the front tank, it stalls out.

I have read a lot of fuel and tank issues, but they all seem to work the opposite way, the front works and the rear has problems.

Would my situation fall into one of these, or is it something else?

 

Most likely the pump in your front tank is dead, it happens to both equally

 

Im having this same problem on my 94. At first it wouldnt run on the front tank, so i had to start it on the rear and flip the switch between front and rear rapidly about 15 or 20 times and then the front tank would work. Then after a while it started right up on the front tank no problem. Now all of a sudden the front tank will just make it stall out and flipping the switch wont do anything.

 

Is there a way to tell if it is the pump, without dropping the tank and replacing it?

 

Put a fuel pressure gauge on the fuel rail, if pressure drops to zero when you select the front tank then the pump ain't working simple as that.

 

Thanks, I'll try that

 

Right, but just because the pump ain't working don't mean it's dead. Another common failure is the selector switch itself, which can disable one of the pumps.

 

Pump failure is *much* more common, tho.

 

I did find a little black box thingy under the dash, to the left of the steering wheel, that had a red button on it.
After following a friends advise, I found it and reset the button.

Apparently, this is a shut off switch in case of rollover or a bad accident. Sometimes the switch needs reset. I am going to see if this works first, then go for the rest, if it doesn't

 

That's the inertia switch, which controls the power to BOTH pumps.

It's likely to be the pump, but it's worth checking out the wiring going to the pump, including the dash switch which the pump current actually runs directly through.

When my pump died, I decided to replace both, and the easiest way to get at both is to pull the bed off.

 

Yea, I just found that the inertia switch definitely was not my problem.

Taking the bed off might not be the easiest for me. I have 2 side boxes full of tools and a metal brake hanging from one of the ladder poles.

It looks as if the straps will be easy to get off, I think my rear tank may have a pinhole leak, so, I may be doing more than I thought, any ways. lol

 

If you do end up replacing the tank, get a plastic one. They're cheaper and they don't rust.