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Just when you think you know ALMOST everything... you get stumped... No start...

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Old Apr 3, 2012 | 08:26 PM
  #1  
huntingman2706217's Avatar
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MJ>XJ
 
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From: Griffin, G.A.
Year: 1990
Model: Comanche
Engine: 4.0 I6
Default Just when you think you know ALMOST everything... you get stumped... No start...

So i pulled everything from my MJ... engine, tranny, and all... rebuilt my engine wire harnesses with new covers and cleaned everything... pressure washed the motor and painted the engine bay and engine... replaced the clutch and tons of other non related stuff... i did swap used 703 injectors in... never ran them yet myself...

has a brand new CPS reading about .350 to 400... i was getting .250-.300 before with the old one and it ran fine but i screwed up and got it to close to the flywheel... hints the new one... which read way more.... the ohm test is good as well...

checked and got power at the ICM under the coil at the proper wires as well as grounds...

battery is grounded to block... block grounded to firewall... block grounded to frame... need to ground battery to fender right at the battery still but dont think its gonna hurt for now...

no vacuum leaks as its all new and replaced now including intake/exhaust gasket...

wont start on starting fluid...

does try and start... slight studder every so often....

timing is correct as well as firing order... plugs, wires, and dist cap/button were new right before tear down...

all fuses under dash are good

I just dont know what to try anymore... lol
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Old Apr 3, 2012 | 08:30 PM
  #2  
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From: Griffin, G.A.
Year: 1990
Model: Comanche
Engine: 4.0 I6
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id like to test things in order as they would happen when going to start the jeep... instead of bouncing around... im not sure of all the different tests i can try on everything... im not looking to fire a ton more of new parts at it... would like to really troubleshoot...
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Old Apr 3, 2012 | 08:43 PM
  #3  
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From: Edmonton
Year: 1990
Model: Cherokee
Engine: 4.0
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Are all mjs renix?
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Old Apr 3, 2012 | 08:46 PM
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From: Edmonton
Year: 1990
Model: Cherokee
Engine: 4.0
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Injector harness wires redone too?
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Old Apr 3, 2012 | 09:16 PM
  #5  
huntingman2706217's Avatar
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MJ>XJ
 
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From: Griffin, G.A.
Year: 1990
Model: Comanche
Engine: 4.0 I6
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Originally Posted by hankthetank
Are all mjs renix?
no... they made them in 91 and 92 which were HO models but more rare to come by in my area anyways... mines renix... 1990

Originally Posted by hankthetank
Injector harness wires redone too?
when i say rebuilt i dont mean by replacing every wire sorry if thats how it sounded... i went through and opened up all the wire looms... fix anything that was ugly... recovered in new red looms and used a aviation water tight tape around the ends... i also sprayed and cleaned out every plug...
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Old Apr 3, 2012 | 09:21 PM
  #6  
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From: Edmonton
Year: 1990
Model: Cherokee
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Not swapped by accident...?
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Old Apr 3, 2012 | 09:42 PM
  #7  
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From: Clarksburg WV
Year: 1995
Model: Cherokee
Engine: 4.0
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I doubt its the injectors because it should start with ether even if the injectors are not working right have you tried pulling a plug or two to see if you got a good spark there
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Old Apr 3, 2012 | 10:10 PM
  #8  
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From: SoCal
Year: 1989
Model: Cherokee
Engine: 4.0
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I was gonna suggest the same as Birdcr125, start with the basics. Pull a plug and check for spark. I would check for pressure at the fuel rail and check the injectors for voltage pulse (all of them).
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Old Apr 3, 2012 | 10:20 PM
  #9  
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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Check for spark. .350 to .400 AC volts from the CPS is a tad low.
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Old Apr 3, 2012 | 10:20 PM
  #10  
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From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
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All fuses and relays are good? As mentioned, no wires crossed? Although, if it tries to light up, I'd imagine everything hooked back as should. Forgive if these have been answered already.. not feeling the greatest and sitting up at 11:20 pm with night time cold/flu in me ain't easy lol.

Also, pull the plugs (also mentioned) and check the spark. Helped a friend with his rig once, and the ignition coil was dying. Caused wierd symptoms, including a couple 'no starts'.

Also, with all the dizzy work and rebuild etc, is the CKPS (or cam sensor, whichever) installed correctly/hooked up/functioning? I've known fellas to rebuild and have issues with the CKPS. Hopefully someone with more knowledge chimes in. Good luck to ya man! I'm gonna go get some sleep... lol
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Old Apr 4, 2012 | 04:12 AM
  #11  
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From: Griffin, G.A.
Year: 1990
Model: Comanche
Engine: 4.0 I6
Default

Originally Posted by hankthetank
Not swapped by accident...?
Naw the way the wires are built in the harnesa there is no way to mix the order up and there 22 years of shaping fell them right bacj into place anyways...

Originally Posted by Birdcr125
I doubt its the injectors because it should start with ether even if the injectors are not working right have you tried pulling a plug or two to see if you got a good spark there
The problem I have run into with doing this before is it may spark but to the eye its hars to tell if its a hot enough spark... Im getting some kind of spark cause it "tries" to start... I never removed the plugs from the head either... Im gonna by a spark tester just to make things easier... Looking back things would have been easier for years now troubleshooting alone... Lol... Ill get to play with it more thur...

Originally Posted by F1Addict
I was gonna suggest the same as Birdcr125, start with the basics. Pull a plug and check for spark. I would check for pressure at the fuel rail and check the injectors for voltage pulse (all of them).
I do need to find those test numbers as well....

Originally Posted by cruiser54
Check for spark. .350 to .400 AC volts from the CPS is a tad low.
We went over this stuff on another mj once before with yas... its not the cps... Im not sure if I agree with that test 100% as this jeep has ran fine and never made more then .300 before the new cps... And it was not hit or miss... It was always hit... .350 is great for this thing and the batt was getting a bit weak when I tested so it may be more...

Originally Posted by 1991Jeep_Man
All fuses and relays are good? As mentioned, no wires crossed? Although, if it tries to light up, I'd imagine everything hooked back as should. Forgive if these have been answered already.. not feeling the greatest and sitting up at 11:20 pm with night time cold/flu in me ain't easy lol.

Also, pull the plugs (also mentioned) and check the spark. Helped a friend with his rig once, and the ignition coil was dying. Caused wierd symptoms, including a couple 'no starts'.

Also, with all the dizzy work and rebuild etc, is the CKPS (or cam sensor, whichever) installed correctly/hooked up/functioning? I've known fellas to rebuild and have issues with the CKPS. Hopefully someone with more knowledge chimes in. Good luck to ya man! I'm gonna go get some sleep... lol
No wires are unplugged... Alls hooked up... Could be the coil... Looks original however was fine before I pulled it... Course it was in the weather... Never pulled the cam sensor... Only the cap and button... But it hung out in the weather as well... So I dunno... Lol... And fuses under dash are good... Relays under the hood on the pass side should be fine but no tellin if they died while out... Not sure what they all do anyways... May not even be related... Lol


Thanks for the help guys
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Old Apr 4, 2012 | 06:22 AM
  #12  
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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Get all the small ground wires on the engine dipstick tube stud?
I noticed you painted your block. Get the paint off the stud before attaching the wires?
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Old Apr 4, 2012 | 07:19 AM
  #13  
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From: Griffin, G.A.
Year: 1990
Model: Comanche
Engine: 4.0 I6
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My grounds are ground to a stud just behind the dipstick bolt... The stud was removed before paint so all ground should be great... I wish there was a way to test them all just in case though... Lol... Any amount of ground will show good on a test light... Lol
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Old Apr 4, 2012 | 08:07 AM
  #14  
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From: Prescott, Az
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Engine: 4.0
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Originally Posted by huntingman2706217
My grounds are ground to a stud just behind the dipstick bolt... The stud was removed before paint so all ground should be great... I wish there was a way to test them all just in case though... Lol... Any amount of ground will show good on a test light... Lol
$10 multimeter set to the lowest ohms scale. Should be required tool for Renix ownership. LOL.
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Old Apr 4, 2012 | 10:04 AM
  #15  
huntingman2706217's Avatar
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MJ>XJ
 
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From: Griffin, G.A.
Year: 1990
Model: Comanche
Engine: 4.0 I6
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Ive got one... Im just not a electrician... So dont really know how to use it... Lol... I dont have a high or low setting or nothing like that... ohms of course but all digital...
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