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How to tell if fuel pump is going bad?

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Old 12-02-2008, 07:39 AM   #1
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Default How to tell if fuel pump is going bad?

Mine is whining like crazy and is pretty loud. Is this a sign of pump failure?
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Old 12-02-2008, 07:41 AM   #2
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Yeah it can be. Have you checked the fuel filter?. Mine was whining last year and i changed the filter and it quit. But im sure it shortened the life of mine significantly.
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Old 12-02-2008, 08:09 AM   #3
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When my pump when out last year, the truck started skipping and sputtering.
Only took about 10 miles before I was stuck on the side of the road.
Try to keep atleast 1/2 a tank of fuel. The pump is actually cooled by the fuel, henceforth making the life last longer.
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Old 12-02-2008, 09:05 AM   #4
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If the fuel pump is going bad you should be able to see it with a pressure guage. You need to hook up a guage where you can see it in the vehicle. Then go out and do some wide open throttle passes. As you get up in the rpms you should see the pressure drop significantly.
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Old 12-02-2008, 09:32 AM   #5
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There is a Schrader valve on the fuel rail to hook a guage in and it should idle at 58-59psi.

My ex's Suburban had a loud a$$ pump but it never went out in the 66k we had it. My Z-71 pump whines sometimes but I am not really worried about it.
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Old 12-23-2008, 03:51 AM   #6
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Quote:
Originally Posted by SOMbitch View Post
There is a Schrader valve on the fuel rail to hook a guage in and it should idle at 58-59psi.

My ex's Suburban had a loud a$$ pump but it never went out in the 66k we had it. My Z-71 pump whines sometimes but I am not really worried about it.
If I hook a guage to it at idle and tape it to the windshield. Put it in drive, and it starts surging, (which is what happens if I don't let it warm up for awhile) Should the pressure hold steady or drop slightly due to the rpms surging? I would think it should hold steady, but don't know.

A link to the other post: http://www.ls1tech.com/forums/genera...-my-motor.html
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Old 12-23-2008, 09:12 AM   #7
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Quote:
Originally Posted by SOMbitch View Post
There is a Schrader valve on the fuel rail to hook a guage in and it should idle at 58-59psi.

My ex's Suburban had a loud a$$ pump but it never went out in the 66k we had it. My Z-71 pump whines sometimes but I am not really worried about it.
suburbans have notoriously loud fuel pumps. ridiculous but they keep working.
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Old 12-23-2008, 09:33 AM   #8
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Quote:
Originally Posted by Hemi Killer View Post
If I hook a guage to it at idle and tape it to the windshield. Put it in drive, and it starts surging, (which is what happens if I don't let it warm up for awhile) Should the pressure hold steady or drop slightly due to the rpms surging? I would think it should hold steady, but don't know.

A link to the other post: http://www.ls1tech.com/forums/genera...-my-motor.html

It should hold fairly steady. The real test is go out and go wide open while watching the gauge. If the pressure drops more than 10 psi you need a new pump. When my pump went out I was going from 60 psi to 35 psi under WOT.
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Old 12-24-2008, 02:59 AM   #9
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couldnt u pull the pump and test it with a car battery? like run 2 wires (positive & negative to the prongs for the fuel pump?
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Old 12-24-2008, 08:28 AM   #10
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Quote:
Originally Posted by nemss1 View Post
couldnt u pull the pump and test it with a car battery? like run 2 wires (positive & negative to the prongs for the fuel pump?
1. Running it dry will hasten it's demise.
2. All that test would show is, it runs. Without a load, the test is pretty much worthless.
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Old 12-24-2008, 02:56 PM   #11
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Quote:
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1. Running it dry will hasten it's demise.
2. All that test would show is, it runs. Without a load, the test is pretty much worthless.
well my car wont run. i pulled the line before the fuel pump and turned the key...no gas came out. starter fluid makes my car start up. i tried to run the pump off of a battery...nothing
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Old 12-27-2008, 06:57 AM   #12
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I changed my fuel filter yesterday and it didn't change anything. Also checked the Fuel pressure regulator hose to see if it had any fuel in it or smell like it. It was fine. So, I guess next I'll check the alternator and battery for free at the auto store. Then I'll break down and buy a fuel pressure guage.

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Old 12-27-2008, 12:55 PM   #13
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would a bad alternator cause a car not to start???

i replaced the battery...still nothing
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Old 12-28-2008, 07:06 AM   #14
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Quote:
Originally Posted by nemss1 View Post
would a bad alternator cause a car not to start???

i replaced the battery...still nothing
That's what somebody over on the truck forum said.
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Old 12-28-2008, 02:10 PM   #15
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Quote:
Originally Posted by Hemi Killer View Post
That's what somebody over on the truck forum said.
could a bad alt cause the fuel pump not to turn on?
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Old 01-01-2009, 12:33 AM   #16
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Quote:
Originally Posted by nemss1 View Post
could a bad alt cause the fuel pump not to turn on?
IDK. This **** is crazy
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Old 01-23-2009, 07:58 AM   #17
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Fuel Pressure:

At Idle - 50psi

5000 - 44-45 psi


So it is my fuel pump, right? Isn't pressure supposed to increase with rpm or hold steady? I've replaced the battery, belt, and alternator about two weeks ago. So I know it isn't that.
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Old 01-24-2009, 08:27 PM   #18
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Unless the trucks are different you should have around 58 psi.
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