1999 4.0 cranks no start no codes no spark? - JeepForum.com

 
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post #1 of 8 Old 05-25-2009, 07:32 AM Thread Starter
relentlessmx
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1999 4.0 cranks no start no codes no spark?

This is my dad's 1999 ZJ with a 4.0. Ran perfectly yesterday, when he parked it in the garage.
Today it cranks & cranks, but doesn't fire.
There is no check engine light on.
I scanned it (think I did it right, virgin scanner) no codes.
I pulled off the spark plug rail & checked for spark at two of the boots, nothing.

Even though my dad knows nothing about cars, he's pretty sure I'm an idiot. That would make this so gratifying to fix...

I'm thinking Crank Position Sensor, any thoughts?
Is there a way to test the CPS prior to swapping it?

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post #2 of 8 Old 05-25-2009, 07:48 AM
gatorayde
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Probably a CPS, at least that would be my guess. If it's a 99, it's called a WJ, not ZJ; just FYI.
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post #3 of 8 Old 05-25-2009, 08:01 AM
LalanP111
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also might want to try the ignition coil, had mine go bad and it did the same thing, cranked but wouldnt fire

1998 TJ, 4.0L, RC 2.5", 31x10.5-15 Duratracs (sold)
1988 MJ, 4.0L ..soon for be on 33's and 6.5" LA/SOA (project)
2004 TJ, 4.0L, Columbia Edition, 2.5" Rough Country, 33x12.5-15 Duratracs, Quadratec Winch, Dual Top (DD, future project)
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It takes care of me and in return, I take care of it. Takes me away from everything I don't want to be around, and back again when needed...
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post #4 of 8 Old 05-25-2009, 08:30 AM Thread Starter
relentlessmx
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Is there a way to test Crank position sensors, cam position sensors, and coil packs prior to replacing stuff randomly?
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post #5 of 8 Old 05-25-2009, 10:32 AM
StellaTheZJ
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Yes there are resistance tests in the FSM. I don't have any info for a WJ (anyone else), but if you google it, they're out there... I understand the CPS usually gives some warning before failing though. Has this truck been getting harder and harder to start, particularly when warm?

It's really unlikely all 6 coils would fail at once, so you're looking for something in common for all of them. Check all the fuses and relays (does the WJ have an ASD?) are free of corrosion on their legs, confirm the alarm is off, make sure there's voltage at the wires TO the coil pack, etc...

Good luck!
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post #6 of 8 Old 05-25-2009, 05:54 PM Thread Starter
relentlessmx
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All fixed... Was the crank position sensor. I had to remove the shift linkage for the trans and use a 18" extension to get at the bolt, took about 2 hours to get 1 bolt out SWEET design!
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post #7 of 8 Old 05-25-2009, 06:09 PM
bcollier1823
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Quote:
Originally Posted by relentlessmx View Post
All fixed... Was the crank position sensor. I had to remove the shift linkage for the trans and use a 18" extension to get at the bolt, took about 2 hours to get 1 bolt out SWEET design!
Gotta love Jeep.
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post #8 of 8 Old 05-28-2009, 04:57 PM
StellaTheZJ
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Ever work on a Toyota? Try removing the intake manifold to get the fuel filter, which should be changed a lot more often than a CPS!!

Try removing the cross member under the tranny next time. If you lower the tranny a bit, the extra room makes the CPS more accessible.
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