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Unread 03-24-2008, 05:46 PM   #1
connor014
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Help!! Jeep is Stalling when hitting bumps!!

So I am on my spring break in Yosemite and my Jeep is acting really weird. I went off-roading up in the mountains a couple of weeks ago and went through some water which is when I first noticed this problem. When hitting bumps it will stall the engine and the check engine light will flash on and the speedometer and tach go down to zero but it will usually keep going (also the gas gauge has been fluctuating with this also). It was fine for a week although I did not drive it much. I drove about 250 miles to Yosemite and only noticed it when I hit big bumps on the road but when I got near the park it got much worse I can barely get around. The engine idles fine though with no problems when I am sitting still. Im not sure if I got bad gas or got water int he tank somehow although I filled up the tank recently when it was empty. I also put in some octane booster and fuel injector cleaner. Any advice on what to check out?? Its a bummer being here in Yosemite without the Jeep for the trails!!

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Unread 03-24-2008, 07:43 PM   #2
connor014
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the engine will actually lug then stop but since i am driving it will turn back over and its always when i hit a bump....its like something is loose maybe electrical but i have looked over most of the connections and havent seen anything loose....i might have to take it into a shop its just theres nothing really close to yosemite
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Unread 03-24-2008, 08:33 PM   #3
chrisjep97
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BUMER....check you wires and connections?
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Unread 03-24-2008, 09:48 PM   #4
connor014
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yeah i really have no idea...im sure it is probably some connection but i have looked everything over...i guess i will have to drive to the nearest town to have them check it out...its just weird it runs fine its just any bumps sometimes it will stall
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Unread 03-25-2008, 10:27 AM   #5
connor014
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yeah i actually did tug on all the accessible connections and hit some of the areas while it was running and nothing...i really have no idea anymore so i will probably have to take it in
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Unread 03-26-2008, 08:32 PM   #6
connor014
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took it in and left it overnight at a shop and they couldnt find anything wrong with it....probably wasnt the best of shops but looks like a have a 300 mile drive back w/a jeep that stalls out on bumps....
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Unread 03-27-2008, 12:08 PM   #7
connor014
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thanks, i am going to go through all the grounds again...also what do you think the possibility of an internal short in the battery when hitting bumps? i did take it offroading pretty hard the day it started...
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Unread 03-27-2008, 12:13 PM   #8
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That's actually a pretty astute thought Connor014, I'd have the battery load tested which could indicate if you have a shorted cell. One thing for sure, the TJ's engine won't run well, often not at all, if the battery isn't putting out enough power for the alternator to work. The problem is that if the possibly broken lead plate isn't quite shorting the cell out except intermittently. Can you temporarily swap batteries with a different vehicle as a test?
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Unread 03-27-2008, 03:29 PM   #9
connor014
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doesnt seem to be the battery....i shook it around a bit and nothing happened and i dont have another one to swap in where im at now....im thinking it has to be something in the wiring harness where the gas guage wires are because at first sometimes the gas gauge would just go out and now its the engine stalling...i will probably just hope it gets me home and take a look in the chiltons guide
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Unread 03-29-2008, 08:14 PM   #10
connor014
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I took it in again and nothing...its hard for them to find a problem when it only happens on bumps...its most likely a ground wire that is loose or a wire that has a short when hitting a bump...to narrow it down what all would cause a jeep to stall if the power is momentarily cut? when it does stall out sometimes the gas gauge will go down to zero and stay there for five or ten minutes then work its way back up so it could be in the wiring harness that involves the gas gauge sensor
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Unread 03-30-2008, 03:38 PM   #11
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Did you check all the wires coming out of your alternator and the chassis grounds? I had alternator lug come loose on my old ford with similar symptoms(the actual lug not the nut). I also had a wire melted on my exhaust in my k5. It was shorting through the exhaust every time i hit a bump and killing the fuel pump. Also check all the main fuses etc make sure they didn't pop out.

Good luck
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Unread 03-30-2008, 03:56 PM   #12
trotter8
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This may be completely unrelated but it sounds like you are out of options. I had this exact same thing happen to me about a year ago. First off I removed my cat for various reasons. When I removed the cat my check engine light went off because my 02 sensor was getting bad readings without the cat "cleaning" my exhaust. So I bought one of those little plug-in adaptors to your 02 sensor that fools the computer into thinking you have a good reading. Anyway, eventually something went funny with the adaptor and it began bumping against my axle every time I hit a bump. This must have caused the adaptor to give a false reading to the computer and it would cause my engine to briefly stall (sometimes until it was completely dead but mostly just stutter). Finally I figured this out and I secured the adaptor so it wouldn't bounce against the axle. Problem was solved.

I don't know if you have one of these cheater adaptors or not, but maybe something is wrong with the 02 sensor after your cat. Try wiggling the 02 wires around while your Jeep is running like that other guy suggested.
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Unread 04-26-2008, 08:50 PM   #13
connor014
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I took it into a mechanic and he thought the computer was bad on it. I dismounted the computer and hit it a bit to see if the jeep would stall but it didn't so I am not sure that the computer is actually bad. Any other ideas?
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Unread 04-26-2008, 08:55 PM   #14
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I'm wondering maybe some of the wires came loose from your fuel pump or a relay or something on that order. Almost seems like its starving for fuel.
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Unread 04-26-2008, 09:17 PM   #15
flatlander757
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Check all the wiring at the fuel pump/sending unit. Sounds like possibly the wires may be rubbing together or touching a ground and shorting out. Or even just pulling out of the back of the connectors.

Also check your crank sensor and wiring, the ASD relay and wiring, and your fuel injector wiring.

As far as the gas gauge itself, when the only problem is the gas gauge reading zero or wrong, it's typically always the sending unit that's gone bad.

Your Jeep will not run without the crank sensor in working order, when they are on the way out, they usually just die without notice or cause severe misfiring, but if it's got bad wiring or isn't securely bolted down I could see it causing your problems, but it still wouldn't explain the gas gauge.

On Dodge Rams and Dakotas, when the rear diff sensor dies, the way to tell is that the MPH gauge will not move until over about 25 or so, then it will jump up and act like normal. I believe the transfercase speedometer gear sensor would take the place of the diff sensor as far as Jeeps are concerned, but that shouldn't cause any drivability problems.
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