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Old 09-28-2012, 08:38 AM   #1
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Highway Speed Hesitation

I just bought my 2001 TJ about 3 weeks ago and I have an interesting issue. When I am traveling at highway speeds it all of a sudden just hesitates then goes back to normal. I notice it sometimes if I hit a bump. It is strange. Sometimes it won't start up correctly, where it feels like it is flooded. But once I get it started and warmed up it seems to be fine. I thought it might be a fuel filter/pump issue but I discovered that that is not a maintenace item since it is in the tank. Oh and it doesn't happen every day either. Please help.

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Old 10-02-2012, 08:01 AM   #2
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Ok well now I think it could be a loose wire or something but I don't know where. If I hit a bump at high speed it completely shuts down for a split second, and today 7 miles down the road from filling it up with gas my fuel light came on and I was struggling to keep it running. Could it be the fuel pump inside the tank, the gas gauge in the tank, is it a clogged filter inside the tank? Please help

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Old 10-02-2012, 10:23 AM   #3
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Can you get your hands on a Fuel Pressure tester? Connect it to the Fuel Rail. Turn your Jeep to ON - you should hear the fuel pump prime. Pressure on the rail should be around 40psi (almost certain) The pressure should maintain that for a little while.

If the pressure drops right away do this: Turn the Jeep to on, not sitting in her. As soon as you turn her on go listen to the fuel tank. If you hear fuel dripping back in it is the Check Valve. I beleive the check vavle is in the Fuel Pressure Regulator. You need to drop the tank to fix that. There are a few posts regarding that fix.

You have me stumped regarding the Jeep cutting off on you? Loose wire for the Fuel Sending Unit? That my also explain your Low Fuel Light?

Let us know pal.
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Old 10-02-2012, 11:10 AM   #4
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Sounds like koopzz is on the right track. Rare but I've seen it happen, the fuel sender supports break and the whole assembly swings in the breeze so to say.

It gets bumped and stops working or swings over and the sender thinks the tank is empty.
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Old 10-02-2012, 12:13 PM   #5
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Quote:
Originally Posted by koopzz View Post
I beleive the check vavle is in the Fuel Pressure Regulator.
There is a widely dissiminated rumor to that effect. The rumor is false.

The fuel pump check valve is located "upstream" from the FPR and seldom malfunctions. The leakdown issue is most commonly due to a failure of the pressure regulator relief valve to seal completely, thereby returning fuel to the tank and emptying the suppy line downstream from the FPR.

Quote:
Originally Posted by koopzz View Post
If you hear fuel dripping back in it is the Check Valve.
You won't hear fuel "dripping" because of a bad check valve. If you can hear dripping, it has to be coming from the FPR. That said, some degree of return is perfectly normal; that's how the FPR works.
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Old 10-02-2012, 02:03 PM   #6
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I will give it a try and let you know. The strange thing is it doesn't do it everyday. Like it did it this morning on the way to work and it may not do it again until thursday afternoon. Anyway Ill keep you posted.

Thanks for the help
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Old 10-02-2012, 03:08 PM   #7
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Well this is interesting. At about 2:30 CDT I went out to start it to see how it was going to start and it took a good long while for it to finally start and when it did start it was not idleing well at all. I drove it down the street a couple of blocks where it hesitated the whole way down there then I let it run for about 10-15 minutes long story short I let it warm up and it did fine. I drove it back to my office and turned it off then turned right back on and it started again. I'm going to go out in about 30 mins and start it again and let it run until i go home from work. I'll let you know how it rides home.
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Old 10-02-2012, 07:25 PM   #8
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Thanks for the leason TangoFax007. I hang my head in shame! I will not repeat that again! (Being sincere here pal - this is why I love these forums)


Baby Daddy: Your Jeep throwing any codes? Check Engine Light on?


Let us know pal
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Old 10-03-2012, 11:33 AM   #9
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Well it ran perfectly last night. I got up this morning and let it warm up to test my theory and it still hesitated on the highway when I hit bumps in the road. I will not have time to look at it for a while either which bums me out. Don't you hate it when life gets in the way of your Jeep?

KOOPZZ no check engine light and I even took it to Oreilly to check and came up empty.
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Old 10-03-2012, 12:29 PM   #10
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@Tangofox, after reading your post it sounds like I need to check my "pressure regulator relief valve" now, theres is only one problem with that....I have NO IDEA where in the heck to even begin to look for that or what it even looks like. Can you lead me in the right direction? Please
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Old 10-10-2012, 08:16 PM   #11
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I changed the fuel pump tonight but I still have a hesitation issue. We'll see how it does tomorrow.
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Old 10-11-2012, 06:06 AM   #12
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The FPR is on top of the fuel pump.

Hold on. I will get a pic...

http://www.wranglerforum.com/f5/repl...tor-79784.html

Sounds as if you have the tank back on. So looks like you get to drop the tank again.

Let us know pal!
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Old 10-11-2012, 08:50 PM   #13
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Well I drive it over 100 miles today and put a new tank of gas in it. It must have been the fuel pump. Thanks for the help.

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