New fuel pump bad?

[SSCalel]

Purchased my first ever wrangler last year to fix up for my daughter to drive. It's a 2001 TJ Sahara with the 4.0. I was told that the fuel gauge works sometimes by the previous owner. Fast forward a year and now it doesnt work at all. So I fought what seemed to be 25 years worth of rusted hardware to finally get the tank dropped and replaced the fuel pump. Reinstalled everything and it does not appear to be working. I didnt have any issues with the old fuel pump, or the jeep running/driving, other than again not seeing the correct fuel level. Just wanted to see if I am missing something or if it is just a bad part out of the box. I tested the fuel and ASD fuses. Fuses were good but I swapped them out anyway. Still tested good. I changed out the relays for both the fuel pump and the ASD figuring maybe I had a bad relay even though everything worked before. I can hear clicking when I turn the key over so they must be good. My battery voltage is 12.2 (battery is a year old) but when I test the power at the fuel pump connector I get 11.3. Not terrible i dont think. The fuel pump doesn't humm like its priming when I turn the key on and of course the jeep doesn't start. Didn't want to try to start it too many times with no fuel. So am I right to assume the new fuel pump is bad? Hate to drop the gas tank again but at least it will be easier this time with new hardware. The only other thing I changed is the oil pressure sensor because I was getting crazy oil pressure readings. Cant verify that that works because I cant start the jeep without fuel. Any thoughts? Thanks!

Chris

 

[Moglocker]

Purchased my first ever wrangler last year to fix up for my daughter to drive. It's a 2001 TJ Sahara with the 4.0. I was told that the fuel gauge works sometimes by the previous owner. Fast forward a year and now it doesnt work at all. So I fought what seemed to be 25 years worth of rusted hardware to finally get the tank dropped and replaced the fuel pump. Reinstalled everything and it does not appear to be working. I didnt have any issues with the old fuel pump, or the jeep running/driving, other than again not seeing the correct fuel level. Just wanted to see if I am missing something or if it is just a bad part out of the box. I tested the fuel and ASD fuses. Fuses were good but I swapped them out anyway. Still tested good. I changed out the relays for both the fuel pump and the ASD figuring maybe I had a bad relay even though everything worked before. I can hear clicking when I turn the key over so they must be good. My battery voltage is 12.2 (battery is a year old) but when I test the power at the fuel pump connector I get 11.3. Not terrible i dont think. The fuel pump doesn't humm like its priming when I turn the key on and of course the jeep doesn't start. Didn't want to try to start it too many times with no fuel. So am I right to assume the new fuel pump is bad? Hate to drop the gas tank again but at least it will be easier this time with new hardware. The only other thing I changed is the oil pressure sensor because I was getting crazy oil pressure readings. Cant verify that that works because I cant start the jeep without fuel. Any thoughts? Thanks!

Chris

Will it fire off carb cleaner?

 

[TJ4Jim]

Purchased my first ever wrangler last year to fix up for my daughter to drive. It's a 2001 TJ Sahara with the 4.0. I was told that the fuel gauge works sometimes by the previous owner. Fast forward a year and now it doesnt work at all. So I fought what seemed to be 25 years worth of rusted hardware to finally get the tank dropped and replaced the fuel pump. Reinstalled everything and it does not appear to be working. I didnt have any issues with the old fuel pump, or the jeep running/driving, other than again not seeing the correct fuel level. Just wanted to see if I am missing something or if it is just a bad part out of the box. I tested the fuel and ASD fuses. Fuses were good but I swapped them out anyway. Still tested good. I changed out the relays for both the fuel pump and the ASD figuring maybe I had a bad relay even though everything worked before. I can hear clicking when I turn the key over so they must be good. My battery voltage is 12.2 (battery is a year old) but when I test the power at the fuel pump connector I get 11.3. Not terrible i dont think. The fuel pump doesn't humm like its priming when I turn the key on and of course the jeep doesn't start. Didn't want to try to start it too many times with no fuel. So am I right to assume the new fuel pump is bad? Hate to drop the gas tank again but at least it will be easier this time with new hardware. The only other thing I changed is the oil pressure sensor because I was getting crazy oil pressure readings. Cant verify that that works because I cant start the jeep without fuel. Any thoughts? Thanks!

Chris

Welcome,

A few easy things you can do, disconnect the FP connector and have someone turn the key to check for momentary voltage at the plug. Test across the 12v lead and the ground while also testing the ground lead to the chassis. If there is any concern for corrosion in the area thoroughly inspect the vehicle side of the FP connector and the wires in the loom directly behind the connector. If you need the wire color codes the service manuals are free to download in the Resources Section....

 

[TJ Jim]

Wonder if you can remove the case on an extra relay and manually engage the fuel pump relay?

 

[SSCalel]

Will it fire off carb cleaner?

Yes. I gave that a try a few minutes ago after reading a different post about intermittent fuel pump issues. And again it previously ran fine until I put this new fuel pump in. But now this thing doesnt do anything. No noise coming from the rear when somebody else tries to start it. I was really just trying to fix the gauge/fuel level issue with this new pump so we weren't guessing anymore how much gas it had in it but obviously caused a bigger issue.

 

[SSCalel]

Welcome,

A few easy things you can do, disconnect the FP connector and have someone turn the key to check for momentary voltage at the plug. Test across the 12v lead and the ground while also testing the ground lead to the chassis. If there is any concern for corrosion in the area thoroughly inspect the vehicle side of the FP connector and the wires in the loom directly behind the connector. If you need the wire color codes the service manuals are free to download in the Resources Section....

I plan on tracing back the wiring today from the FP to the relay. I wasnt figuring that was the issue since everything was running before with no issues but you never know. The connector for the new fuel pump was a little bit of a pain to plug into the vehicle side plug. I pulled it all apart and looked to make sure that no pins were resessed or bent but everything feels tight. Testing the wire again I was getting 11.3 V at the FP plug to ground.

Thanks for the heads up on the service manuals. I'll be sure to download them.

 

[SSCalel]

Wonder if you can remove the case on an extra relay and manually engage the fuel pump relay?

How would you do that? I am willing to try it.

 

[TJ4Jim]

Have you tried connecting the old FP at the connector to see if it responds.

 

[Moglocker]

Have you tried connecting the old FP at the connector to see if it responds.

 

[TJ Jim]

How would you do that? I am willing to try it.

https://wranglertjforum.com/threads...-the-fuel-pump-relay-with-a-paper-clip.52994/

 

[SSCalel]

So just to give an update. I ended up dropping the fuel tank and replacing the fuel pump since it was under warranty and everything seemed to be pointing towards the new part not working. Got everything installed with the new pump in and she fired right up and works like a champ. Fuel gauge reads accurate as well. Thanks everyone for the help!!!

 

[Chris]

So just to give an update. I ended up dropping the fuel tank and replacing the fuel pump since it was under warranty and everything seemed to be pointing towards the new part not working. Got everything installed with the new pump in and she fired right up and works like a champ. Fuel gauge reads accurate as well. Thanks everyone for the help!!!

Thanks for the update. Glad you got it resolved!

 

[Hopper]

So just to give an update. I ended up dropping the fuel tank and replacing the fuel pump since it was under warranty and everything seemed to be pointing towards the new part not working. Got everything installed with the new pump in and she fired right up and works like a champ. Fuel gauge reads accurate as well. Thanks everyone for the help!!!

Glad you got it fixed. What FP did you use?

 

[B1Toad]

So just to give an update. I ended up dropping the fuel tank and replacing the fuel pump since it was under warranty and everything seemed to be pointing towards the new part not working. Got everything installed with the new pump in and she fired right up and works like a champ. Fuel gauge reads accurate as well. Thanks everyone for the help!!!

If it's not too late, don't toss the old pump. There is a good tutorial on here about how to rebuild it with a new Bosch pump. Mopar pumps are NLA and there are lots of threads here about how unreliable many of the after market replacements are with some folks replacing them 2 or 3 times in a short time frame. If you can rebuild the old one you will have a better pump than money can buy. If you don't want to do it, at least send me the pump!

 

[Bigfoot-NM]

If it's not too late, don't toss the old pump. There is a good tutorial on here about how to rebuild it with a new Bosch pump. Mopar pumps are NLA and there are lots of threads here about how unreliable many of the after market replacements are with some folks replacing them 2 or 3 times in a short time frame. If you can rebuild the old one you will have a better pump than money can buy. If you don't want to do it, at least send me the pump!

Link to referenced tutorial?

 

[B1Toad]

Link to referenced tutorial?

V

Thread 'How to replace your fuel pump without replacing the whole assembly'

Dec 21, 2021

Ok, I figured I'd post this here since I haven't seen it anywhere else. I've been chasing a hard start issue on my tj and got down to the in tank pump. I knew the sending unit was still good, but wanted the peace of mind of having a new pressure regulator and pump. I also didn't want to fork over ~$200 for a new assembly when I knew I could find a pump and regulator for much less. I didn't take pictures during the process because I'm a dumba$$ and this was the last thing I did on a Saturday so I was ready to be done. This only applies for 97-04 TJ's I believe. Assuming you've managed to...

• vrtillman
• Replies: 22
• Forum: TJ How-to Guides

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