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Unread 12-31-2011, 07:07 PM   #1
dillonjm
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Excess pressure in the gas tank

Anyone ever had this happen?:

Was wheeling when my fuel pump got a little louder than normal, sounded like a power steering pump that was low on fluid, how it has kinda a weird whine. I stopped to see what the deal was and popped the gas cap only to have it spew fuel like the girl in exorcist spews pea soup. In all seriousness it probaly shot a cup or so of gas out the filler.

I had almost a full tank when this happened, I backed up onto level ground and turned the Jeep back on and it built up some pressure again, but no where near what it had when it was on a slight uphill.

I realize that the fuel will move back in the tank when going uphill and into the filler, but it seemed weird that it built up enough pressure to shoot some out of the filler cap. It didn't spill, it shot.

Any ideas? It seemed to be ok after driving it back to the trailer... the fuel pump was nice and quiet again too...kinda weird.

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Unread 01-01-2012, 12:20 AM   #2
dillonjm
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I'm all alone.. may just let it go and see what happens
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Unread 01-01-2012, 12:25 AM   #3
BackRoadJPin
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Bad gas cap maybe? They are designed to relieve pressure and in Utah (Salt Lake County) they will fail your emissions test if they cap is not functioning properly.
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Unread 01-01-2012, 12:45 AM   #4
Joe Dillard
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I know this article doesn't cover YJ's, but it sounds like it could be related.

http://www.safetyresearch.net/2011/03/23/fuel-spit-back-continues-to-plague-chrysler-vehicles/

I have seen this happen firsthand to a friends YJ. His spewed ALOT and IIRC the fuel tank expanded quite a bit.

Any chance your exhaust is leaking/allowing excessive heat to expell near the tank?
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Unread 01-01-2012, 12:48 AM   #5
dillonjm
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It was all new exhaust until I kinked the downpipe today by trying to use it as a skid plate, however, I doubt its building excess heat.

Its odd. I'm gonna check all the lines and make sure I didn't kink one somewhere. I never had this issue until this afternoon. Will have to diagnose further, like I said the issue went away at the end of the day. Cap is also new.

Thanks for the input/links both of you.
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Unread 01-01-2012, 05:30 AM   #6
timatoe
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I had the pressure issue happen to me once, this past Sept. A little background, my YJ had a stock steel 15 gallon tank, over the summer I swapped that out with an early stock 20 gallon tank. I don't know the year of the tank, but know it was an early model based on not having a fuel pump built into the tank. Anyhow, no problems after install and then in Sept, after Labor Day I drove to the Rubicon, about two hours from my house, as I was coming onto the trail I stopped to air down and could hear hissing coming from the right rear corner. I tracked it down to the overflow valve up in the rear passenger wheel well. Popped the gas cap, which is a stock TJ cap from when I relocated the filler, and it was hissing and blowing out of the cap. I stuck a screwdriver into the filler to flip the little flapper valve open and a big whoosh came out of the filler and then continued to vent out the entire time I aired down. I kept an eye on it the entire week and it never happened again, and hasn't happened since. I'm at a complete loss as to why it happened or what caused it. No gas spewed out but I was at about a half a tank when it happened, if it had been full without a doubt it would've sprayed out like the ones in Joe's link.
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Unread 01-01-2012, 07:26 AM   #7
Perkalater79
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Quote:
Originally Posted by timatoe
I had the pressure issue happen to me once, this past Sept. A little background, my YJ had a stock steel 15 gallon tank, over the summer I swapped that out with an early stock 20 gallon tank. I don't know the year of the tank, but know it was an early model based on not having a fuel pump built into the tank. Anyhow, no problems after install and then in Sept, after Labor Day I drove to the Rubicon, about two hours from my house, as I was coming onto the trail I stopped to air down and could hear hissing coming from the right rear corner. I tracked it down to the overflow valve up in the rear passenger wheel well. Popped the gas cap, which is a stock TJ cap from when I relocated the filler, and it was hissing and blowing out of the cap. I stuck a screwdriver into the filler to flip the little flapper valve open and a big whoosh came out of the filler and then continued to vent out the entire time I aired down. I kept an eye on it the entire week and it never happened again, and hasn't happened since. I'm at a complete loss as to why it happened or what caused it. No gas spewed out but I was at about a half a tank when it happened, if it had been full without a doubt it would've sprayed out like the ones in Joe's link.
What was your elevation gain from home to the trail where you got the big woosh? How full was your tank? Have you traveled that elevation since then? I wonder if the circumstances were just right for the tank to build up more pressure than it could release. I've had wooshes like that before. Usually involves altitude, temperature changes, etc.
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Unread 01-01-2012, 12:23 PM   #8
NHfireYJ
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Quote:
Originally Posted by Joe Dillard View Post
I know this article doesn't cover YJ's, but it sounds like it could be related.

http://www.safetyresearch.net/2011/03/23/fuel-spit-back-continues-to-plague-chrysler-vehicles/

I have seen this happen firsthand to a friends YJ. His spewed ALOT and IIRC the fuel tank expanded quite a bit.

Any chance your exhaust is leaking/allowing excessive heat to expell near the tank?


Side bar...

Thanks for that like Joe... My GF 2008 patriot started doing that... Dealer charged her $220 to replace the " check valve" . Even though she had extended warranty which included the fueltank where the valve is. Problem continued, took it back and they put a 2nd check valve in and refunded her the charges from the first install...

Now back to the thread....
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