Off topic 89 f150

[fordman]

I have a 89 f150. 6 cyl 5 spd. Dual tanks. This truck has three fuel pumps. One high pressure pump on the frame and a low pressure pump in each tank. The truck will sometimes start and run for a few minutes. But will bog out and die if I try to put in in gear and take off. I can hear the frame pump come on when the key is on. This is when the truck will start. If I don't hear the pump. The truck won't start. I figure the hp pump is bad. Maybe. Unless one or both low pressure pumps aren't pump lung fuel to the hp pump. Opinions? Could bad low pressure pumps make the hp pump not work properly or shut down or off until fuel is to the hp pump. Truck has sat for a few years.

[Ranchero50]

Tired pumps maybe, clogged filter most likely or possibly a bad fuel pressure regulator. When it dies, cover the shrader valve on the fuel line and pop the pin to see if you get fuel out of it. Regulator and check ball in the pump discharge should keep the line pressurized.

[1972hiboy]

Thing to do would be getting a fuel pressure gauge hooked up to the rail and verify your suspicion of fuel starvation. Then start working backwards testing individual components. If you do indeed verify fuel starvation as the cause of your stalling, and it does it with both fuel tanks then its probably worth doing fuel filters first then the common pump before trying to go after individual tanks.

[1970FordTK]

Don't forget to check the fuel pump relay.

[fordman]

I know there is no fuel when it dies. Im trying to determine if all pumps are dead or just the low pressure ones. Or maybe its just the hp pump. Does it matter if the tank low pressure pumps work or not? Could non working low pressure pumps starve the hp pump?

[fordman]

Update. I remove the line between paper filter and hp pump. Turned on key got gas coming from front and rear tank. Very low pressure like a regular electric pump would do. So those pumps should be good unless intermittent. I sprayed carb cleaner in throttle body and the iac motor. . None of that helped it still died after a few minutes or if I put it in gear to go. So I replaced hp pump with a junkyard hp pump. It ran longer than usual. Then it did the same thing bogged out and died. Frame Fuel filters are clear both of them. What to look at next. I have not been able to check fuel pressure after it dies. Which I'm going to do next.. Unless it's losing power to fuel pump is other thing I thought of.

[DIXONBOY]

This may not necessarily be your problem but they had a recall on some of those to were they put one way valves on the fuel pumps. They were pumping from one tank to the other. I guess that could make low fuel pressure but I don't know for shure. If you leave one tank empty will it eventually fill up. I know that's hard to test now but has it in the past?