I just bought a 1997 f250HD 351 5sp and There's an occasional hesitation only when I'm using the rear tank. As soon as I switch to the front tank, it's fine. Then I can switch back to the rear. The prior owner told me that it started about 3 months ago. So I'm thinking fuel pump maybe? Other thoughts?

 

I just went through this a few days ago..I was having the exact same problem on the rear tank of my 96 f250...It would hesitate when I would gas it, if I floored it WOT would fall flat on its face.. Anyway awhile back I had installed an adustable FPR with a FP guage, I was adjusting my fuel pressure the other day and I noticed lower pressure and the needle "bouncing" while switched to the rear tank.... I couldn't adjust it higher than about 36psi and when I gave it gas the pressure dropped big time... Anyhow tuesday I went ahead and dropped the rear tank and replaced the pump.. Problem solved, runnin 41psi now on both tanks at idle and the needle is rock solid.. No more hesitation..... The pump was pretty spendy though at $140...

 

Thanks, that's what I was thinking but I hadn't put a gauge on it yet.