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Unread 07-09-2010, 09:10 AM   #1
bcusstc
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1995 YJ Wrangler 
 
Join Date: Mar 2010
Location: Jersey Shore, PA
Posts: 377
Fuel Pressure reading..Help!!

Having troubles trying to figure out what the %%%% is wrong with my XJ.

Ive done fuel pressure readings and it is 31ish with vacuum plugged in and it bounces from 31-38ish with vacuum unplugged, Wasnt sure if that should be a steady pressure or if its suppose to bounce up and down from 31-38ish.

she idles great, Starts great, just can NOT figure this out..
Ive done new plugs, wires ,rotor cap ,distb cap, fuel filter, tps, IAC, New grounds, ive unplugged and reset the CPS, replaced the fuel relay, 02 sensor,

as soon as i give it gas it will go but it has a hesitation or surge that just seems fuel related. i can floor it and it will hesitate a little bit but it will still accelerate.

Will a clogged strainer give me these hesitation issues?
Any help would be greatly appreciated.

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Unread 07-09-2010, 09:45 AM   #2
Paradise XJ
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1990 XJ Cherokee 
 
Join Date: Jan 2007
Location: Paradise, CA, Northern California
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Did you adjust the TPS? On your RENIX the TPS is adjustable and should be adjusted when newly installed. That sounds like what your problem is.

http://www.greatlakesxj.com/tech/TPS.html

If you have 31 psi on the schrader valve, you should be good, doesn't sound like a fuel issue.

How did you "reset" the CPS(CKS)??
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Unread 07-09-2010, 09:56 AM   #3
bcusstc
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1995 YJ Wrangler 
 
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Location: Jersey Shore, PA
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i didnt adjust the tps i took it out of another running cherokee to be honest.
but i did check my tps before and it checked out ok.

I had unplugged the battery and the CPS for a few minutes to see if that would help as well.
i can rev it up all i want with no problems no nothing. sounds great no issues what so ever. its when i put it in drive and go do i get the hesitation. Coil maybe? Should the pressure jump up and down with the vacuum unplugged?
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Unread 07-09-2010, 02:32 PM   #4
cruiser54
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You absolutely have to adjust the TPS. Stop all other plans, diagnoses etc etc and adjust it with a voltmeter. Otherwise you are just peeing into the wind.
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Unread 07-09-2010, 03:57 PM   #5
bcusstc
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after running a volt meter on it, it shows me 4.5 volts going in and 3.8 coming out.
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Unread 07-09-2010, 05:48 PM   #6
cruiser54
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1990 MJ Comanche 
 
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Location: Prescott, Arizona
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With that input voltage, it should be 3.78V coming out. Always take your input voltage and multiply it by .83 to get the proper output voltage on an automatic. Time to adjust your messed up TPS.
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