wont start still!!! - JeepForum.com

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post #1 of 17 Old 06-29-2013, 06:05 PM Thread Starter
lance89xj
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wont start still!!!

I have an 89 Cherokee 4.0l. one day it was running just fine the next it just cranks but wont fire up. I have replaced fuel pump and filter, dizzy and roter and cap, plugs and wires, ICM and coil and the CPS. oh and the timing chain and gears. still nothing. I did a compression test and it was all outta wack so I pulled the head off and had it shaved and one valve seal fixed. put it all back together and its still doing the same thing it was before I started replacing stuff. please help im at wits end with this.

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post #2 of 17 Old 06-29-2013, 07:03 PM
tjwalker
It's the crank sensor!
 
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You need to do some basic troubleshooting to see what you are missing. Fuel, spark and compression.

1. Do you have a strong, BLUE, snapping spark?

2. Do you have approximately 31 psi of fuel pressure at the fuel rail measured with a fuel pressure gauge?

3. What do you mean by the compression was out of whack? What were the "before" and "after" compression readings. The spec for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

Gotta start with the above three things.

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post #3 of 17 Old 06-29-2013, 10:25 PM Thread Starter
lance89xj
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okay so I just cheaked the spark and its bright blue. and the compression is #1,80 #2,80 #3,75 #4,90 #5,95 #6,95. now im gonna run to the parts store to get a fuel presior tester.
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post #4 of 17 Old 06-29-2013, 11:28 PM
Hudson
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Fuel is not your problem.


I mean it could be, but something is seriously wrong internally with that engine. None of those cylinders are within spec.

Did you do a wet compression test or dry? (Wet compression test is when you add oil to the cylinder to see if the rings(?) are sealing.)

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post #5 of 17 Old 06-30-2013, 12:46 AM Thread Starter
lance89xj
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I did a dry test. and ill do the wet test tomorrow along with a fuel pressure test. It sounds like its super close to starting when I add fuel in the T.B. witch leads me to belive its a fuel problem.
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post #6 of 17 Old 06-30-2013, 12:51 AM
xrunndonex
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hook up jumper cables and crank away don't crank to long and give it like minute breaks to recharge mine did that once turns out I got a battery with hardly a charge on it
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post #7 of 17 Old 06-30-2013, 01:18 AM Thread Starter
lance89xj
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nope its not the battery.
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post #8 of 17 Old 06-30-2013, 01:19 PM
Kalali
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What's the point in trying to start an engine with that much compression? You'll soon need to add a starter and battery to the list of parts that you'll be replacing. Isolate the cause of low compression between the valves and the rings and fix the root cause. How many miles on the rig?
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post #9 of 17 Old 06-30-2013, 01:50 PM
MarkwithaK
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My '98 did this when I first bought it. Ended up being the ignition coil.
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post #10 of 17 Old 06-30-2013, 04:01 PM Thread Starter
lance89xj
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there is 207XXX miles. its got a new battery when I bought it. and its got a new coil too. I guess I need to do a wet test and see if the rings are sealing or not
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post #11 of 17 Old 06-30-2013, 04:26 PM
xrunndonex
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Quote:
Originally Posted by lance89xj View Post
there is 207XXX miles. its got a new battery when I bought it. and its got a new coil too. I guess I need to do a wet test and see if the rings are sealing or not
How many times have you tried to start it?
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post #12 of 17 Old 06-30-2013, 05:03 PM
cruiser54
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Sure seems as if some thorough diagnostics in the beginning woulda been good instead of shotgunning parts and stuff. Just sayin. I'm wondering if the cam is timed correctly.

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post #13 of 17 Old 07-01-2013, 04:49 AM Thread Starter
lance89xj
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Quote:
Originally Posted by xrunndonex View Post
How many times have you tried to start it?
probly 20 times or more.
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post #14 of 17 Old 07-01-2013, 04:51 AM Thread Starter
lance89xj
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Quote:
Originally Posted by Kalali View Post
What's the point in trying to start an engine with that much compression? You'll soon need to add a starter and battery to the list of parts that you'll be replacing. Isolate the cause of low compression between the valves and the rings and fix the root cause. How many miles on the rig?
207700 miles on her
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post #15 of 17 Old 07-03-2013, 04:13 PM Thread Starter
lance89xj
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Okay so due to everything being good except for the compression im going to replace the piston rings and inspect the lifters and camshaft now. keep yall updated
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