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Unread 11-10-2013, 03:12 PM   #1
mopar
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4.7L won't run longer than 5 min???

I'm working on a 2002 wj 4.7 for a friend that will not run longer than 5 minutes. sometimes it will crank right up and sometimes it turns over for a while before it will start. Sometimes it will run longer than others but no longer than 5 minutes. when it does run, it has the power it supposed to its just like you turn the key off.

My first guess was the fuel pump but it has a steady 55-60psi fuel pressure and doesnt die like its running out of fuel and pressure doesn't drop till after it dies.

Sometimes it will die like you turn the key off and sometimes it will cut out and pick back up a time or two like the switch was cut off and back on, run fine for a second and die. It doesn't slowly die out like its running out of fuel. It acts more like a spark/injector issue so i'm kinda leaning toward a cam/crank sensor issue.

It does have a CEL but i don't have anything to check it with at the moment.

I just thought I could get a few opinions on here until i can get my hands on a scanner for further info.

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Unread 11-10-2013, 03:24 PM   #2
alfaitalia
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You don't need anything to check that cel....just do the key dance and the codes will pop right up on the odometer. Its on off on off on with key the going as far a dash lights on but not cranking...if you did not already know that!

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Unread 11-10-2013, 04:43 PM   #3
mopar
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sweet! didn't know that! ill check that and get back with the codes
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Unread 11-10-2013, 05:14 PM   #4
mopar
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Okay, so im pretty sure its a cam/crank sensor problem now. any ideas on where i can find the specs to test these sensors with a meter?

P0340-Cam position sensor circuit malfunction
P0420-catalyst below threshhold bank 1
P1391-Intermittent Loss of CMP or CKP
P0442-evap system control leak detected(small)
P0455-evap system control leak detected(large)
P0456-evap system leak detected(small)

I had the gas cap off trying to see if i could hear the pump running is more than likely the reason for the evap codes.
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Unread 11-10-2013, 08:12 PM   #5
PhantomWJ
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just replace the crank position sensor...
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Unread 11-10-2013, 08:32 PM   #6
Jeeples
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Originally Posted by PhantomWJ View Post
just replace the crank position sensor...
With a Mopar sensor. Don't waste your time with parts store replacements.
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Unread 11-10-2013, 08:33 PM   #7
OffroadOran
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Quote:
Originally Posted by jeeples

with a mopar sensor. Don't waste your time with parts store replacements.
x2
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Unread 11-10-2013, 10:41 PM   #8
mopar
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pretty common failure part on these?
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Unread 11-11-2013, 06:05 AM   #9
OffroadOran
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Quote:
Originally Posted by mopar
pretty common failure part on these?
Yea the crankshaft position sensor tends to fail on our jeeps, i had to do mine over the summer. Mine would just Not start without one day and low and behold it was the p0320 code (along with some other weird fan relay codes cause of the constant cranking). I had a trustworthy friend put in the sensor and i havent had the problem since. Mopar sensors only, since any other brand of sensor has a higher chance of causing more problems and you dont want to do the job twice
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Unread 11-13-2013, 11:27 PM   #10
mopar
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finally got around to getting the old one out this afternoon after realizing its not on top of the transmission like i'm used to on the older stuff. i'm gonna grab a new sensor tomorrow and hope that does the trick cause the cam sensor looks like even more of a pain to get to.
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Unread 11-13-2013, 11:51 PM   #11
PhantomWJ
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Quote:
Originally Posted by mopar View Post
finally got around to getting the old one out this afternoon after realizing its not on top of the transmission like i'm used to on the older stuff. i'm gonna grab a new sensor tomorrow and hope that does the trick cause the cam sensor looks like even more of a pain to get to.
Ih....nope. the crank is harder to get to...the cam is in the open, so to speak.
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Unread 11-14-2013, 10:11 AM   #12
Jeeples
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Yeah, cam sensor is pretty easy on the 4.7's. It's not necessary, but I like to pull the battery tray and give myself plenty of room to work. Even the crank sensor isn't terrible, just pull the starter and slide it out of the way, should have plenty of access to pull the crank sensor mounting bolt. Prying the old sensor out can be a PITA though.
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Unread 11-14-2013, 09:21 PM   #13
PhantomWJ
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Oh..im thinking he has the 4.0... Oooops.
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Unread 11-15-2013, 08:21 AM   #14
mopar
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yeah I found that out after pulling the battery tray. But the cam sensor is what was wrong with it anyways. so hopefully I won't have any problems with it since it now has a new crank and cam sensor. lol
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Unread 11-15-2013, 08:51 AM   #15
rdkendrick
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Quote:
Originally Posted by mopar View Post
yeah I found that out after pulling the battery tray. But the cam sensor is what was wrong with it anyways. so hopefully I won't have any problems with it since it now has a new crank and cam sensor. lol
Keep us informed. I'd like to know what finally fixed it. Good luck!

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