I have a 1990 Ford E250 extended van with a 351W w/fuel injection and duel gas tanks. I was driving along the freeway running on the front gas tank (16 gal). The engine started to hesitate a little and it progressively got worse until it quit altogether with one-half tank of gas left. After pulling over I switched tanks (rear tank was full) and the engine started and I was on my way. When I started going uphill there was again hesitation but very minor when I was pulling small hills. The hesitation while still minor got worse the stepper the incline. I replaced the fuel pump in the front tank and the truck seemed to run fine around town. On my next trip the hesitation started again while running on the front tank and became quite bad but the engine never quit (with one-quarter tank of gas). I pulled over shut it down and switched to the rear tank and continued on. Again I had slight hesitation but nowhere near as bad as on the front tank. Both times I noted a slight smell of bad gas while running on the front tank but the gas in both tanks was fresh and I could not detect a bad gas smell from the tanks (sniffed at the fill pipes).

Does anyone have a suggestion on what the problem could be or at the least where to start looking.

 

might have water in the front tank. left over water in the line woould make it run rough on the other tank. just a thought might be wrong.

 

dump some HEET in both tanks, replace the fuel filter and doesnt that rig have a pump in each tank and a pump on the frame as well? the frame mounted pump if there is one may be going bad. also pull codes www.fordfuelinjection.com

 

I also agree. I would check the inline pump right behind the fuel filter. It is gravity fed, it does not pull fuel very well. So if you get a hesitation, it might not be pumping right. One way to check would be to pull the fuel line off the back of it, hook up a fuel hose to the back and run the other end of the hose to a 5 gallon can. It is not designed to pull fuel all the time but it should have enough power to pull it from the 5 gallon can. Thats how I checked mine.

It may sound redneck, but hey whatever works.

 

My dilemma in figuring out this problem is that it the hesitation doesn’t start until I drive the truck for approximately one and one-half hours on road trips. The hesitation has started on the last two road trips I’ve taken. I thought it may be a low fuel level in the front tank but driving it around town or on short trips on the front tank even with a low tank of gas (less than Ľ tank) there is no hesitation. I’m also baffled as to why, when the hesitation starts it is much worse when running on the front tank than it is while on the back tank (very slight hesitation while on the back tank). I’ve considered the fuel pumps, one in each tank and one on the frame rail, the fuel filter and, as I stated previously, I replaced the fuel pump in the front tank after the first occurrence. I found the tank very clean inside with no debris or water when I put the new pump in. The fuel pump filter was clean also. I am further baffled because if this were an electrical or sensor problem I would think the hesitation would be the same regardless of which fuel tank was being used.

What am I missing?

And thank you in advance for any guidance or direction you can give me!

 

might be in the switching valve. i think it has a pressure operated valve. could be dirty or the diapham coming apart.

 

To all that responded,
Thank you for you input. This was an odd one but now that I found the problem, as it always is with hindsight, it should have been painfully obvious.

Todd, you were right it was the fuel-switching valve. I took it apart and found that the valve that controls the fuel going from the tanks to the engine was hanging up resulting in the valve only being partially open regardless of the selected tank. I suspect that because the hesitation was worse on the front tank the valve was stuck in the mostly closed position for that tank. And no I didn’t try to make it work, I replaced the whole thing. I haven’t’ yet taken a road trip to verify that all is well but an reasonably confident that the problem is solved….if not, as California governator Arnold would say, “I’ll be back”.

Thanks again to all…..This is a great forum.