Please disregard my signature - that's a different truck. This one is 1989 f250 with 351 v8 gas engine.

I am in the middle of a messy, drawn out R/R of both fuel tanks, featured by only a bit of time here and there and then lo and behold the wrong rear tank being delivered in the mail.

Anyway, I have replaced the front tank and the truck will run for about 10 KM on the front tank, then stumble and stall. Can crank and start it, will stumble and stall again. If I switch to Rear tank for even 5 seconds when running, then switch back to Front tank, it will run another 10 km or so, then stumble and stall again. Plenty of fuel in the front tank.

Maybe the front tank's pump is weak, and over a bit of time, pressure bleeds away to the point that the motor stalls? Switching to rear tank with strong pump repressurizes system again... ? Just my ideas, but I'd sure appreciate some input. The truck was doing this a little bit before I removed the front tank, but I chalked it up to maybe a bit of condensation or somehting, as the tank had previously been empty for a long time on account of the leaks.

thanks for any ideas.

 

Only way to tell for sure is put a fuel pressure gauge on it. Tape the gauge where you can see it while driving and take it for a ride.