When I bought my 96 f-150 the rear tank was near empty and the front tank was full. The previous owner told me that the gas in the front tank was bad and needed to be drained out. The truck runs absolutly fine on the rear tank but when you switch to the front tank you lose a little bit of power. The amount of power flucuates though from running almost fine to not accelerating at all and even stalling. If I switch to the front tank on the interstate it will keep the cruise control speed for about 1-3 minute and then just stop accelerating all together, the more throttle you give it the faster it slows down.

This leads me to believe that it is a problem with the fuel filter or the pump. I am looking for suggestions on this issue. Does the front and rear tank have independent fuel pumps? What about fuel filters? Where is the fuel filter and pump for the front tank located? Any other suggestions highly appreciated.

 

Yep, separate pumps. Going to the same inline filter outside the tanks. Check fuel pressure at the rail for both tanks. That will tell you if it's bad gas or a bad pump. If it's bad gas, toss a can of Seafoam in it or drain it.

 

So the guy told you the gas was bad, and you havn't drained it, but can't figure out why the truck runs bad on that tank?

 

Well the reason I don't think the gas is completely bad is because it will run ok on the front tank for a few minutes and then it just drops out like it completely loses fuel pressure or something. I would be more inclined to believe that it was "just" bad gas if I was getting more consistent crappy running. My number 1 suspect is the fuel pump. I believe it just isn't maintaining the fuel pressure which is why it runs ok for a few minutes. Now I do believe the gas is slightly old but it still runs. I won't be able to dig into this problem for a few weeks so I was just trying to get some insight in the mean time.

Maybe a stupid question but want to be sure, is the fuel pump located inside the tank? How much work is involved in swapping out the pump? Just trying to get an idea. Thanks for the help guys, I really appreciate it.

I think that he truly thought that it was bad gas, but he only owned the truck for 4 months and said the tank was half full when he purchased the truck and he filled the tank up. This just seems like a more complicated problem than simply bad gas considering the symptoms.

 

It could be bad gas, it could be the pump. It could also be that there's crud in the tank which clogs the strainer sock on the pump after it runs for a few minutes. When you shut it off, the crud drops off the sock settles down to the bottom of the tank and you start over again. The only way to find out is to drain the tank and see what comes out and whether the problem goes away.

The pump is in the tank. Changing the pump on a full tank is a PITA; you're way better off pulling the bed than dropping the tank. With an empty tank, it's probably easier to drop the tank. You'll need a set of garter spring tools and some dielectric grease to swap the pump