TBI fuel pump.. test?

[kevinr1970]

In talking to guy about a '90 Suburban, he said the fuel pump was bad, but the truck runs real good.
I asked why he thought the pump was bad and he said that it quit running so he had a friend turn the truck over while he banged on the tank with his hand and it started right up?
He said if I wanted to see/hear it run he would bang on the tank while I started it.
Why would hitting the tank affect the pump working or not, outside of maybe a short in the wiring?

[pontgta]

Loose electrical connection or could possibly be the pump is stuck. You can hear the pump while turn the key foward momentarly. If you can not hear the pump then ther is an issue.

[kevinr1970]

Originally Posted by pontgta

Loose electrical connection or could possibly be the pump is stuck. You can hear the pump while turn the key foward momentarly. If you can not hear the pump then ther is an issue.

So what if you can't here it, until you hit the tank?
I am cool with it needing a pump, I might even have one in my '91 parts Suburban.
Just curious why hitting the tank would do anything!

[pontgta]

If you can't hear, i would say more than likely be pump. But I would check it just in case. sounds like an easy fix because if it you can crank the engine and keep it running with that same pump.

[SCOTI]

Banging on the tank sometimes frees the pump up & they start working (just like whacking a old stubborn sbc/bbc starter).

[Bigstevex4]

Yes that trick does work sometime have ever bhad and elec house fan you had to kick start same thing.

[kevinr1970]

Went and looked at it last night and the battery was toast and wouldn't take a charge.
It did have enough juice from the charger that when the ignition was turned on I could hear the pump go.
Going back Friday with a good battery and a gallon of fresh gas to see if we can't get it started, it has not been driven in over a year.

[kevinr1970]

So I brought a good battery with me and it fired after three cranks (hadn't been started in at least a year).
Test drove it around the neighborhood, but I trailered it home since it was around 20 miles and didn't want a gremlin striking someplace between.
Got home started it drove it off the trailer, drove it to the gas station later that day and put some gas in it, shuffled the trucks around the back yard the next day.
Started and ran each time?

[SCOTI]

Originally Posted by kevinr1970

So I brought a good battery with me and it fired after three cranks (hadn't been started in at least a year).
Test drove it around the neighborhood, but I trailered it home since it was around 20 miles and didn't want a gremlin striking someplace between.
Got home started it drove it off the trailer, drove it to the gas station later that day and put some gas in it, shuffled the trucks around the back yard the next day.
Started and ran each time?

Pull the pumps out & check the fuel transfer hose between the pump & the discharge lines out of the tank. Very common to have a weak hose w/the ethanol in the fuel dissolving the rubber hose (not rated to be submersed in ethanol).

[Damien]

I bought a '87 Jimmy and was told the fuel pump was out, but the truck started and drove fine around town and one highway trip. The second highway trip the pump went out completely. I felt pretty dumb when I had to pay the $175 tow bill when I had a new Delco pump at home. The motor in the pump will develop a dead spot and banging on the tank jars the pump enough to get past the dead spot. As long as it does not stop in the dead spot it will function but it could still be worn out giving lower fuel pressure which will affect performance and driveability.

[motornut]

check the power to the pump,I found a corroded cut in my wire over the wheel well.
after replacing the pump in my 87,and it still died