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HELP - Fuel pump question - first time post


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barcode2328
New User

Jan 19, 2013, 8:59 PM

Post #1 of 4 (1475 views)
HELP - Fuel pump question - first time post Sign In

Hello,

This is my first post here, and I really hope someone can help me out :). I have a 2001 Chevy Malibu (3.1 V6), and right now it will not start. I have a hunch that the fuel pump is the culprit, but I wan't to see what you guys think.
After the no start, I listened for the fuel pump by cycling the key to on and off. When cycled I could hear a very faint hum for a second or two, but just barely. Even taking off the gas cap and putting my ear up to it, I really couldn't hear anything but I could hear a hum coming from somewhere.
After that, I checked the relay and it was clicking. I also checked the fuse and that seemed good. My next step was to hook up a pressure gauge to the fitting on the fuel rail. When I cranked the car over, there wasn't any pressure that the gauge was registering though.
I decided to change the fuel filter since that hasn't been changed for a while, but when I removed the old one, I left it off to test. With no fuel filter in place I cranked the car a bit (battery was dying, so just a little). I figured there would be a good puddle of fuel under the car, in a pan, but there wasn't anything (I do have fuel in it :) ). I figured that this would point to the pump then.
I did put the filter in place and try and crank it a little, and just like before, it didn't start and nothing would register on the gauge. After pulling the gauge off though, there was a little fuel that dripped off of it when I disconnected it.
Do you guys think it is the fuel pump? I don't want to replace it and such and then have it be something else :(. Is there anything I missed? I appreciate it!

Thanks


Sidom
Veteran / Moderator
Sidom profile image

Jan 19, 2013, 10:08 PM

Post #2 of 4 (1440 views)
Re: HELP - Fuel pump question - first time post Sign In

Well you got some important checks already done & thats good.....You've verified no pressure so you're half way home...

The thing with electrical......you can't go by looks good or sounds good......That will get you in a world of hurt real quick....

The last thing you need to do is verify power down at the pump.......go back to the tank & disconnect the fuel pump connecter........There should be 4 wires....You want to test for 12v on the gray wire & ground on the black wire.......You can use a volt meter or test light...put on end on the black wire & the other end on the gray wire......Have a helper turn the key to the on position.......there will only be power on the gray wire for 2 seconds......If the PCM doesn't sense the engine start in that time frame....it turns the power off....

If you have 12v on the gray wire and a good ground on the black wire......then you have a bad fuel pump......The new one should come with a new connecter......change it......don't look at the old one & think it "looks good"....change the connector......Also make sure the new pump has a sending unit on it...if it doesn't, you need to swap the old one to the new unit.......


(This post was edited by Sidom on Jan 19, 2013, 10:11 PM)


barcode2328
New User

Jan 20, 2013, 9:05 PM

Post #3 of 4 (1397 views)
Re: HELP - Fuel pump question - first time post Sign In

Thank you. Yeah, I got a chance to test out the voltage off of those wires and sure enough it hit 12 volts for 2 seconds and then dropped.
With your advice, I am now confident that the problem is a faulty pump. Thanks much!Smile


Sidom
Veteran / Moderator
Sidom profile image

Jan 20, 2013, 9:11 PM

Post #4 of 4 (1395 views)
Re: HELP - Fuel pump question - first time post Sign In

Good job on testing out the circuit.......Good luck on the pump






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