94 f 250 tow rig is suffering from rear tank fuel starvation. under load pulling 24ft enclosed trailer, boged down (lost power) almost to the point of not being able to continue to move. exhaust was smoking hot (literally). idled ok. switched to front tank, all was good. towed from BG KY to Clev. OH. tried rear tank again after cool down time. same result. believe the rear in tank fuel pump is bad, but un sure if other comp. in system could cause same resilts, ie relays for pumps, switching valve ect. any one had this problem? my experience with fuel pump failure has been total shut down, no pump, no run. any reason to believe it is anything but the pump?
thank in advance for any help
Adam
NMRA O/C #10

 

has to be the pump..... I believe that the relay is before the tank switch. I suppose you could have a bad ground on that tank tho.

 

monitoring pressure at rail now, but can't get failure to repeat local ford dealer tech said he thought it was a plugged or kinked rear tank return line causing high pressure so rich, allowing raw fuel to burn in the exhaust, causing the hot exhaust. front and rear are acting exactly the same, pressure is 30 (on deceleration) to 45 (riding the brakes and hammering it to simulate load). going to hook up trailer tonight and try again.
thanks
Adam