i have and 87 f150 302 with dual tanks, today while driving home on the rear tank after driving on the highway, i was sitting at a stop light and the truck decided to start to run rough then smooth out, well i go to turn and the thing would not get outta its own way. like a huge miss. Now i switch over the to the front tank and within about 30 seconds seemed to run fine, so i switched back over to the rear tank and didn't run as bad but not as good as the front tank. Also when sitting for a while it's hard to start, crank no fire right away, and now this, I'm wondering if this sounds like a fuel pump starting to go or what? the pump itself does not sound bad but i don't really here a nice solid pump noise when the key is first turned before start up. And finally, From what i think i see there is one pump on the drivers side frame rail. Is this correct and since i don't have any fuel gauges to judge pressure what else could it possibly be? thanks.

 

You have 3 pumps, one lift pump in each tank, and the high pressure pump on the frame as well as a switching mechanism. Sorry I forget what its called.

 

The fuel system has nothing to do with it getting fire.
Sounds like maybe the TFI Module on the side of the distributor or the pick-up coil inside the distributor is going bad.

If you mean it is getting spark and not starting then you may have a bad rear boost pump.

 

well i just tested the rear tank switching to the front tank and the rear tank makes it run bad, and the front the truck runs fine. So i'm still leaning toward the pump on the frame and i'm gonna be putting in a new side tank aka front anyways, so i might as well replace the pump/sending unit while in there too.

 

oh also, has anyone did away with the rear tank or side tank all together or is there too much modification involved to do this?

 

The hi-pressure pump on the frame is used with both tanks.

 

You would have to replace the selector valve with one from a single tank truck (non switching) and just plug the lines from the tank you want to use into the reservoir. Then leave the switch on the dash switched to the tank you have left.

 

You might want to search on the selector valve, I beleive theres a way to clean and check it. I doubt its the hi-pressure pump too.

 

selector sounds more like it. so you think that it could be clogged or something of that nature? for the rear tank? and thanks for that diag. Looks great.

 

now does any standard part store carry these? thanks.

 

You can only get the selector valve from Ford for about $115.00.

 

I vote for the pump in the rear tank or the switch on the dash.

 

don't forget the hard starts and today no problems running off the rear tank