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Discussion Starter #1
I have a 2000 Chevy S10 ZR2 with about a 160,000 on it. Well I encountered something weird with it.

The truck runs fine, fuel pressure was about 45 at idle, and 60 at startup.

What happens is the fuel pump relay gets hot. It won't die when it's running, but as soon as you turn it off, and try to turn it back on. It won't do anything. All power to the pump is gone.

But when you switch the relay with one from the AC, or horn, that uses the same GM fuse. It works fine and starts right up and runs like nothing happened.

And after the relay cools down, the relay will work just fine.

This is a very intermitant problem. It doesn't do it everytime. It has went as long as a month without a problem, and has happened as many times as 3 different times in one day.

I'm thinking because it is intermitant, is it maybe a bad ground somewhere? That is all I can possible think of. Would the ground be the one on the harness by the tank? Or is there one up by the fuse relay box.

The only thing else I can think of, is the problem started after I left my wife start driving the truck. My wife uses AC like it is going out of style, where I will not use it and haven't used since I bought the truck two years ago. The problems started when she first started using AC, and I do notice if I turn on the AC, the fuel pump relay does get warmer faster, and seen it quit after my wife drives with AC on several occasions. Especially driving in town in stop and go traffic. It does seem to have somewhat a corrolation with the AC. Whether it's just coincident or not, I don't know.

Any or all help will be appreciated!
 

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Have you tried replacing the relay with a new one, or does it happen with any relay that you try? Does it ever blow the fuse?

I would check the ground at the tank harness for sure. A definite problem area. Also check the connections on the harness for any signs of corrosion or high resistance. Some fuel pump kits come with a replacement harness to install with a new pump.

And don't be too hard on the wifey about the A/C. Down here in Texas we can go all day with the A/C on Max, and rarely have a fuel pump problem. I've replaced one fuel pump in 10 yrs. and 207,000 miles.
 

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Discussion Starter #3
Yeah I tried a new one didn't make any difference. Tried a couple of them. All from GM as well. They seemed to last longer than the old ones, but they still did it eventually.

I did put a new fuel pump in, but it was a Delco so I used the stock wiring harness. That was actually one of the reasons I did that because I didn't want to replace the harness. And the aftermarket ones you had too.

I will have to get up and see if I can see the ground wire under there. I think if I remember right it was at the top of the frame above the tank. But I can't remember. It's been about 1 year since I did it and I have a 3 day memory! lol

Thanks!
 

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You should know better than to let a female drive your truck!:rant:

No, it sounds like a weak connection or shorted windings in the pump.
Pump windings want to draw a certain amount of power under load, and when a connection like a weak ground happens the voltage across the pump goes down, the voltage used across the week connection goes up so the pump will draw more current and heat the relay up. When the relay heats up, turn on your back parking lights and see if they look dim. They share the same ground lug to the pump. Also, make sure the neg battery wire to the frame isn't getting warm. You can always add another ground wire.

Also, consider changing the fuel filter. If it's gunked up, the pump is just going to have to work that much harder.
Good Luck.
 
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