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  #1  
Old October 13th, 2009, 21:03
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WeeTodd WeeTodd is offline
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1991 XJ Will not start HELP!!

Ok so I just got a 1991 Cherokee inline 6 4.0L HO for $300 It was not running when I got it and is still not running.
I'm stumped it has all the things it needs to run but it won't.

I have a new fuel pump. I checked the fuel at the rail and there is pressure
I have over 120 psi per cylinder
I have spark at all 6 cylinders
and I have air
I think the timing may be out but not sure how to change it or if it is even possible

so I have all the things I need to run but it does not run

I tried changing the ecu but that did not help
I also unplugged the CPS and then there was no spark and reconnected it and the spark came back.
I TDC the crank and the rotor and cap line up with #1 cylinder
I also tried quick start and that did nothing so itís not a fuel problem cause I could smell it on the plugs when I pulled them
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  #2  
Old October 13th, 2009, 21:14
joe_peters joe_peters is offline
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Re: 1991 XJ Will not start HELP!!

Air, fuel, compression, spark--what else could you ask for? Having all of the above at the right time and place.

Check the CPS/CMP (camshaft position sensor), it provides a synch signal for firing the injectors.

Have you tried a NOID light to see if the injectors are in fact firing?
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  #3  
Old October 14th, 2009, 09:10
tims92xj tims92xj is offline
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Re: 1991 XJ Will not start HELP!!

I'm not sure about the 91 but on my 92 inline 6, timing is not adjustable. According to chilton/haynes manuals, timing is only adjustable on the 4 cylinder and v6.

Oseberg posted this link to help me with a timing issue. See if this helps:

http://www.go.jeep-xj.info/HowtoEngineInstall4.htm
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Old October 14th, 2009, 10:14
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winterbeater winterbeater is offline
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Re: 1991 XJ Will not start HELP!!

Even though timing mark and cap/rotor line up, the distributor could be 180 degrees out of phase with the crankshaft. It has to be TDC on compression stroke. This can be verified by checking at the spark plug hole for pressure or removing valve cover and checking that #1 exhaust and intake valves are closed.
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Old October 14th, 2009, 13:17
trinappa trinappa is offline
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Re: 1991 XJ Will not start HELP!!

If there is no crank maybe the crank position sensor
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  #6  
Old October 17th, 2009, 11:12
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Re: 1991 XJ Will not start HELP!!

Quote:
Originally Posted by joe_peters View Post
Have you tried a NOID light to see if the injectors are in fact firing?
Can you tell me what a NOID light is??
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  #7  
Old October 17th, 2009, 11:27
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wim hoppenbrouwers wim hoppenbrouwers is offline
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Re: 1991 XJ Will not start HELP!!

Hallo, (sorry Joe)
A noid light is a little lamp or led to see or the wiring to the injector is giving an electric pulse.



wim

p.s. Thanks to McQue

Last edited by wim hoppenbrouwers; October 17th, 2009 at 11:32.
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Old October 17th, 2009, 11:31
joe_peters joe_peters is offline
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Re: 1991 XJ Will not start HELP!!

Quote:
Originally Posted by WeeTodd View Post
Can you tell me what a NOID light is??
It is a flashlight used by the Domino's Pizza Noid.

A noid light is a small device used to test the fuel injection signal to a single injector. The signal can't be read by a normal test light or multimeter.

http://www.google.com/imgres?imgurl=...ed=0CA8Q9QEwAQ
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  #9  
Old October 17th, 2009, 18:00
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WeeTodd WeeTodd is offline
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Re: 1991 XJ Will not start HELP!!

Installed a new CPS

Checked if it was 180deg out of phase it is not

Installed a used rotor/distributor/cam shaft sensor

and it wont fire!!!!

there must be something up with the timeing I spray quick start in it and nothing happens so it is not a fule problem!!!

I just dont know????
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Old October 17th, 2009, 18:09
joe_peters joe_peters is offline
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Re: 1991 XJ Will not start HELP!!

Quote:
Originally Posted by WeeTodd View Post
Installed a new CPS

Checked if it was 180deg out of phase it is not

Installed a used rotor/distributor/cam shaft sensor

and it wont fire!!!!

there must be something up with the timeing I spray quick start in it and nothing happens so it is not a fule problem!!!

I just dont know????
OK, back to basics.

Hook a multimeter to the battery terminals. What is the static voltage?
What is the voltage when cranking?
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  #11  
Old October 17th, 2009, 19:28
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Re: 1991 XJ Will not start HELP!!

Quote:
Originally Posted by joe_peters View Post
OK, back to basics.

Hook a multimeter to the battery terminals. What is the static voltage?
What is the voltage when cranking?

12v static
11v cranking
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  #12  
Old October 17th, 2009, 19:38
joe_peters joe_peters is offline
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Re: 1991 XJ Will not start HELP!!

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Originally Posted by WeeTodd View Post
12v static
11v cranking
Ok, that is good. Reason I asked is you can have plenty of amps for cranking but too little voltage for the engine's electronics. Less than 9 volts things don't work like they should.

Again, basics.

Condition of the spark? Blue, really snaps or yellow?
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  #13  
Old October 17th, 2009, 20:11
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Re: 1991 XJ Will not start HELP!!

Spark looks good nice and blue
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  #14  
Old October 17th, 2009, 20:14
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Re: 1991 XJ Will not start HELP!!

I also unpluged the
MAP no change
IAC a couple times it woud fire while I am cranking but woud not start
TPS no change

unpluged all of them Nothing
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Old October 17th, 2009, 20:41
joe_peters joe_peters is offline
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Re: 1991 XJ Will not start HELP!!

Quote:
Originally Posted by WeeTodd View Post
I also unpluged the
MAP no change
IAC a couple times it woud fire while I am cranking but woud not start
TPS no change

unpluged all of them Nothing
Ok. You are saying it is firing when cranking but dies when the key returns to the RUN position?
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