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  #1  
Old August 7th, 2022, 08:54
Lost_Wrench Lost_Wrench is offline
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Fuel Pump Thermal Failure?

I just got back from a weekend camping trip and my 96 XJ has developed a starting problem. It is having trouble re-starting for the first few minutes after running at temp. Symptoms are rough low idle/dying/rich smell and the fuel gauge drops all the way down to empty and the low fuel light comes on. It does not help much giving it gas when this happens. After a few minutes it starts up fine and normal. No check engine light has come on.

The fuel pump and module is the crown automotive 5003869AA from quadratec and it has less than 2k on it so I'll be bummed if it's already going. The only thing I haven't done yet is test the fuel pressure while this is happening. Sound like pump failure or possibly something else?
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Old August 7th, 2022, 09:04
Ralph77 Ralph77 is offline
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Re: Fuel Pump Thermal Failure?

My first question is how much gas is in the tank when this happens?
Fuel cools the fuel pump.
So with a defective pump and a 1/4 of a tank I could see this happening.
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Old August 7th, 2022, 09:41
Lost_Wrench Lost_Wrench is offline
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Re: Fuel Pump Thermal Failure?

The very first time it happened was actually at the gas pump right after I had filled it. I had just gone over a high mountain pass and came into a small town to fill. This morning it did it again with 1/2 tank.
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Old August 7th, 2022, 17:14
lawsoncl lawsoncl is offline
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Re: Fuel Pump Thermal Failure?

I wonder if you have a bad ground at the gas tank? Lifting the ground on the fuel gauge will cause it to read empty.
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Old August 8th, 2022, 04:51
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cruiser54 cruiser54 is offline
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Re: Fuel Pump Thermal Failure?

This^^. And, a poor ground will cause the fuel pump to get hot.

http://cruiser54.com/?p=249
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Old August 8th, 2022, 14:20
Lost_Wrench Lost_Wrench is offline
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Re: Fuel Pump Thermal Failure?

Thanks guys I hadn't considered the FP ground wire. Interesting that it's behind the spare tire. Cruiser54 thanks for that link on shortening the ground wire!
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Old August 13th, 2022, 10:25
Lost_Wrench Lost_Wrench is offline
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Smile Re: Fuel Pump Thermal Failure?

SOLVED

The other day It drove to work just fine but at the end of the day when I went to start it up and go home it cranked endlessly, and I could not hear the fuel pump priming. I started tracing wires and checking grounds, including the one suggested behind the spare tire. I didn't find anything that looked loose or badly corroded so I tried starting it again and it fired right up and made me very confused. While it was running I got underneath and started wiggling wires. I barely touched the main wire harness going to the fuel pump and the jeep sputtered out and died. That was the culprit. It must have originally had a retaining clip on it to keep it from coming apart that now looks broken because it had simply wiggled loose. I reconnected it securely and put a ziptie around it and have had no problems the last several days. It is still strange to me why I mostly had issues after warm-up but that was definitely the issue. Thanks all for your suggestions, I learned some new things and it wasn't an expensive fix so it's all good for now.
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Old August 13th, 2022, 13:10
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cruiser54 cruiser54 is offline
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Re: Fuel Pump Thermal Failure?

Excellent job of finding the issue!!
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Old August 13th, 2022, 15:57
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Re: Fuel Pump Thermal Failure?

Thanks for the update.
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  #10  
Old August 15th, 2022, 13:24
maxbraketorque maxbraketorque is offline
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Re: Fuel Pump Thermal Failure?

Good info.
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