need help diagnosing a fuel pump prob. on 89 f-350

[mikey's250sx]

yesterday for the second time my truck wouldn't start. i used it all morning and in the afternoon i parked it at a turkey hill to get coffee and when i came out it wouldn't start at all. it cranked and had spark because when i sprayed carb cleaner in the throttle body it fired. so i figured it was getting no fuel. so first i pulled the fuel filter off the frame rail and then cranked it. well no fuel came out the fuel pump. so i figured it was bad. but when i turn on the ignition i can hear it click and run for 2 seconds so i wasn't sure about that. i went to autozone and they said there are 2 pumps. one on the frame rail i could see and one on the front tank. great. i went back now thinking the rear pump was bad and not sending gas to the front pump. well i can't get to the rear pump because the fuel tank has to come down. so i figured i would have it towed to a shop where i get my work done today. i woke up early and figured i would give it one more try at banging the tank,pump,filter,and tugging on every electric wire and connection i could see. i got out there about 7 and thought just for shits and giggles i would try one more time first. i still had the fuel filter off from yesterday so i started cranking and low and behold i start making a puddle on the ground.

so overnight something happened that let the fuel flow resume. the truck never moved so i didn't make a loose connection or wire start touching again. it just sat for 12 hours.

any ideas? if i take it to a shop it will cost at least 100 bucks in labor just to pull the tank and check the rear pump which today is working fine. i really don't want to run up a few hundred dollar bill while they search for the problem.

has this ever happened to you?

thanks,
mike

[Jason Hall]

Those electric pumps do some stupid things when they are going bad. My bet is the pump is bad & it is randomly shutting down. Once it sits for a while it will start again. You can probly plan on putting a new pump in the tank, so start spraying your tank strap bolts.

[Howdy]

I never had this sort of problem. All the pumps I had go bad died and stayed dead.
As far as the pump turning on when the ignition switch is initially turned on. And running for a few seconds and then shutting off ( with the ignition still on ), is 100% normal. What is happening is the pump is running to charge the system with fuel. The pump does this in 2-3 seconds. Being as you can hear the pump run, I would say you can almost totally rule out the pump being bad. But to test it further you need to put a pressure gauge on the fuel system up by the motor. If the truck is fuel injected there should be a connector on the fuel rail some where. The fuel rail is the tube that carries fuel to all the injectors. It's normally a chrome tube.

If your getting good fuel pressure to the motor, then your fuel pump is most likely good. There is still a slight possibility it is bad, it's very slight ( IMO ).
I hope this helps.
Howdy

[Jason Hall]

From what I understood you are hearing the front pump run. Is it the front pump you hear running? The pump in the tank feeds the pump on the frame rail. The pump in the tank is a slow turning low pressure pump that feeds the high pressure pump on the frame rail. If you took the fuel line off at the filter & had no ruel pressure, then did'nt touch anything all night & came out in the morning & had fuel pressure I would bet on the low pressure pump in the tank. I never understood how two pumps are better than one. I guess it gives you another thing to have go bad. I have seen lots of electric pumps go bad all the suddon. It's not uncommon, when the pumps start to wine real loud you can bet they will be junk soon. An intermittent problem is hard to find, sometimes you wont find it until it totally quits.

[mikey's250sx]

yeah i can hear the high pressure pump on the rail but i can't turn on the ignition and get to the tank fast enough to hear tht one. a new pump for the tank is 100 bucks so when i have time in the next few weeks i may pull the tank down and replace that one. the hard part is it is my bucket truck that we use for work so i have to know i won't need it for a few days.

[200xman]

I had an 89 Dodge TBI and a 91 Bronco EFI That both did the exact same thing you are talking about. The Dodge did it for a while until I figured it out, the Bronco did it twice before it died completely. Good luck dropping the tank.

[phreakboy]

it does sound like the pump in the tank, if the tank is mounted lengthwise on the passenger side, you can usually get away with just dropping the back clamp and takeing out the pump, if it is a flat square tank in the back than you could always do it the oldskool redneck way and just cut a hole in the bed with a sawzall directly above the tank, I have seen that done many of times