Hello. 1988 F350 460 7.5l gas. The vehicle has a hard start 5-10 secs then starts, idles a little rough fuel pressure 29psi. Fuel pressure drops immediately when turned off or not under a load. The problem is consistant with either tank selected. The fuel pump on the rail is running the whole time, when the front tank is selected the front fuel pump runs, the back does not. When the rear tank is selected the front does not run and the rear pump Does NOT run. Its a Dump truck so the pumps is are easily assessible. I changed the fuel filter and fuel regulator. I just bought the truck so I have no history on it. At 2000 RPM the truck runs and sounds very smooth, no misfires. I believe its the rear fuel pump, instead of being a parts changer I want to understand the process of a dual tank truck, since it will be a work truck. Thanks guys! New subscriber today.