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Discussion Starter · #1 ·
Hey guys, in the middle of my first fuel pump replacment. Not as bad as I thought, yet... We'll see if it actually fires up when I'm done. But that brings me to my first question. Looking at the harness my purple and black wires look great. Shielding is all the way to the top and meets up into the black clip, The Grey wire however is exposed a little bit. Is this common? Or has the harness gone south? I tried to post piccs but my phone is being lame. I'll try to get some up soon. Any quick response would be great. I need it for work tomorrow morning. ha
 

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You mean where it passes through the bulkhead?

Are you replacing the in tank harness [the one inside at the pump]? You should, they're available at most auto parts stores for under $20 which is cheap insurance.
 

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Discussion Starter · #4 ·
Yes It's the one inside the tank. I'm guessing looking at it and reading other posts that that is prob what actually failed and not the pump. Since the tank is dropped anyway, I'm going to replace the pump and sock anyway. So, your thinking the wire is most likely bad?
 

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Hard to tell from here if it was a wiring or pump problem or if the issues were related [i.e: failing pump drawing more amps] but replacing the in tank pump harness would be a good idea while it's out. It's the connector pins inside the connectors that cause the overheating/wiring damage. It's a poor design and as pointed out above, soldering the wires is the best option if you can solder correctly.
 

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Discussion Starter · #6 ·
*Update* Installed new pump with new in tank harness. Pump still will not turn on. However when I was popping on the connectors, the "Square" style one feels very loose. If looking at it when off it looks like two little metal tabs are sticking out at a 90 degree angle. The old one I pulled off did not have that design. I'm wondering if its loose and not making a good connection or while installing the pump may have just fallen off completely since it's loose. Any thoughts? Maybe the wrong harness the "Braniacs" at the autoparts store grabbed?
 

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The in tank harness is a "generic" harness meaning it will fit several different GM models. You must make sure the correct style and color wires go exactly where your originals did. The instructions are a little difficult to understand but if you read it a few times it should make sense which one of the applications your is. You need to figure out which wires yours used and their style and color position in your old harness. Not all the wires are used, it depends on your application. To release the individual wires from the connectors you just insert a pin or paperclip down in the connector to release then position the wires within the plug like your originals. I should have been more specific I guess but I assumed you would understand the directions. It's been long enough since I did mine that I unfortunately can't walk you through each wire and where it goes from memory. It's a bit frustrating but once you understand it you'll get it. If the wires aren't correct, it will never work or the pump could run in reverse.

There was a decent write up somewhere on here but I couldn't find it prior to posting.
 

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Unplug your fuel tank harness at the rear of the car and put an ohmmeter across the gray and black wires. If you get an open circuit or a really high resistance, then you've got a bad connection to the fuel pump. The stock fuel pump resistance is usually 3-10 ohms. As a check, put the ohmmeter between the purple and black wires and you should get something between 0 and 140 ohms. That will indicate that the connections to the fuel gauge sender are still good.
 

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Discussion Starter · #9 ·
Still frustrated...

Update....Hooked up a volt meter to the plug at the back of the car that runs uptoward the trunk lid. Did not get 12v from the time the key was on to turning it off. It jumped around from 5.0-8.5v, then would drop to millivolts.

Does the computer tell that plug to turn on? Where should I go from here?
 

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Check the fuel pump relay under the hood. You can also bypass the relay and jump the pump directly to the battery positive terminal (only do this to test, do not leave it that way). If all that is good, it could be in the wiring harness comming from the engine bay towards the back.
 
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