Jeep Cranks but Wont start. Is it CPS?
#1
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Year: 1999
Model: Cherokee
Engine: 4.0 L Straight 6
Jeep Cranks but Wont start. Is it CPS?
My '99 xj was driving fine all week and today i hopped in and it wouldn't start. The engine cranks but it wont turn over. I am able to push the gas while turning the ignition and the engine will rev but as soon as i let off the gas the engine dies off. Any clue as to what it could be? I have read that a common problem is the CPS but if the CPS was bad wouldnt the engine not rev since i wouldn't be getting a spark?
#2
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Year: 1996
Model: Grand Cherokee
Engine: 4.0l 6 cylinder
i get that when the battery has been completely drained for the first 10 mins after a jump start.
i am no mechanic but i don't think this is a crank shaft position sensor issue. yes it will stall your vehicle if its going out but not consistently every time you let off the gas. my jeep currently is down to this issue and the heat outside keeping me from doing any real work.
but your problem reminds me of a dirty, failing or failed oh heck what did they call it something like an iac control.
mine was not bad just dirty, took off the air box housing and hose, i ended up taking off the carb and cleaning the whole thing instead of just that part this jeep i bought somehow had sand all over in the airbox, carb, and on that part, probably only got an air filter put on just before i bought it.
i couldn't get that part off itself which is why i took the whole carb unit off.
anyways thats my thought could be right could be wrong but cleaning it would never hurt especially if its not been done in a long time.
ryan
i am no mechanic but i don't think this is a crank shaft position sensor issue. yes it will stall your vehicle if its going out but not consistently every time you let off the gas. my jeep currently is down to this issue and the heat outside keeping me from doing any real work.
but your problem reminds me of a dirty, failing or failed oh heck what did they call it something like an iac control.
mine was not bad just dirty, took off the air box housing and hose, i ended up taking off the carb and cleaning the whole thing instead of just that part this jeep i bought somehow had sand all over in the airbox, carb, and on that part, probably only got an air filter put on just before i bought it.
i couldn't get that part off itself which is why i took the whole carb unit off.
anyways thats my thought could be right could be wrong but cleaning it would never hurt especially if its not been done in a long time.
ryan
#4
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Year: 1992
Model: Cherokee
Engine: 4.0
when you step on the gas while cranking it will spin over faster as it can not SUCK air in as apposed to throttle butterfly being shut.. do you have spark ? do you have fuel pressure ?
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#8
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Year: 1987
Model: Cherokee
Engine: 4.0
When my CPS went down(and out of the blue-no warning symptoms at all), the engine would just crank with no firing at all... Took me three weeks(here and there fiddling on it) to narrow it down to CPS(process of elimination). Once i spent the time kissing the tranny/flywheel putting it in and rigging a magnetic fishing hook(since one bolt fell into flywheel), fired right up!
#9
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Year: 1993
Model: Cherokee
Engine: 4.0
probably a bad IAC/clogged iac. Pull the throttle body and clean iac and passage and hopefully that fixes it or worst case you need a new one. oem is best but i used a SMP iac from rockauto and it's still going
Also post your tps readings especially the throttle closed reading
Also post your tps readings especially the throttle closed reading
Last edited by dac612; 09-21-2016 at 04:25 PM.
#13
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Year: 1995
Model: Cherokee
Engine: 4.0
Make sure you can test for " pending codes " if there is no CEL ( Check Engine Light )
If I have a suspicious condition, I drive around for few miles with the scanner hooked up monitoring and recording data .... sometimes a fault will pop up without setting off the CEL and then clear themselves.
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Year: 1999
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