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-   -   Cranking not starting unless jumped (http://www.jeepgarage.org/f77/cranking-not-starting-unless-jumped-47557.html)

it2swbrown 09-17-2012 05:10 AM

Cranking not starting unless jumped
 
Hey guys. First post here but I am out of ideas.

I drive a stock 2000 Cherokee limited 4.0 with a hair under 150k miles on it. For about 2 months it is having a starting issue when cold. In the mornings I have to have it jumped or connect a battery pack on it to get it to start.

Brand new battery, alternator is good, fuel pressure is good, can hear the fuel pump when key is on, all lights inside/outside are good except for headlights but I believe that is a switch issue because brights work fine, voltages are good.

Weird thing is that when warm (around 1pm or 2pm) it will start just fine. It cranks and cranks but just won't start when cold. If I start it every hour or hour and a half it will crank through the night.

I have replaced the battery cable terminals because there was no crank voltage. I do have a bad fuel injector 4 but the mechanic I talked to said because it will start when extra juice is applied that shouldn't be the cold start issue. He said he didn't want to keep taking money from me and keep just throwing parts at it with out knowing the exact issue. He said best bet would be to take it to a dealership and have them check it out. I will do that today but wanted to see if anyone on here has heard of this before.

I am thinking either the cps or pcm but am not sure. I am no where near a mechanical person.

Any help is appreciated.

Jeff

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2005JGC 09-17-2012 06:13 PM

Re: Cranking not starting unless jumped
 
I would check your powers and grounds, its not uncommon for corrosion to build up in the cable. A voltage drop measurement over your + and - cables. I suspect you will find excessive resistance somewhere in the circuit. When its cold there is more of a demand on the starting system cranking over the cold motor, pumping the thick cold oil... and resistance will create more of a problem.

it2swbrown 09-17-2012 06:26 PM

Quote:

Originally Posted by 2005JGC (Post 684793)
I would check your powers and grounds, its not uncommon for corrosion to build up in the cable. A voltage drop measurement over your + and - cables. I suspect you will find excessive resistance somewhere in the circuit. When its cold there is more of a demand on the starting system cranking over the cold motor, pumping the thick cold oil... and resistance will create more of a problem.

Thanks for the reply. Should have also stated but forgot to include that I replaced the battery cables as well when I replaced the terminals. I have it at the dealer now overnight so that they can try to fix it when it isn't starting. I will post what they say. Everybody I talk to about it always says to let them know what the issue is because it is so strange. Even the dealer mechanic looked kind of baffled.

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it2swbrown 09-18-2012 05:31 PM

In case anyone has a similar issue, it turned out to be a combination of my crank position sensor being bad and an intermittent starter contact issue. Replaced both the cps and starter. Hopefully in the morning it will start now.

Edit: Started up perfectly this morning.

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