no spark,1990 cherokee sport 4.0l - JeepForum.com
 
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post #1 of 4 Old 04-25-2010, 09:35 PM Thread Starter
mike13
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1990 XJ Cherokee 
 
Join Date: Apr 2010
Location: Arvada,Co
Posts: 2
no spark,1990 cherokee sport 4.0l

Please help!ran fine the day before the problem but the next morning wouldn't start.just cranks over.I have already changed the cap,rotor,coil,icm,and cps.Could it be the ecm?Thanks in advance

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post #2 of 4 Old 04-25-2010, 10:36 PM
HenryKrinkle
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1988 XJ Cherokee 
 
Join Date: Apr 2010
Location: WI
Posts: 187
Well, you should probably check all your grounds and connections. You've checked for spark and still nothing? If so, the neutral safety switch has been known to cause no-start situations. Try starting it in park and in neutral. Not sure if it's the nss or the cps that could start in N vs P.

Could it be a fuel issue? Maybe your pump is shot, something along those lines. Look up fuel pressure tests in your manual or online.
Or a preliminary test: I think you just pull the 4 bolts off the rail, wiggle the injectors loose without turning them too much. Then you would find something to catch the fuel spray with (*Fire extinguisher handy) and turn it over. Pretty sure all should spray at first.
If that's good: do your pressure test.
If that's bad: probably fuel pump.

Whenever you remove the injectors it's a good idea to replace the o-rings. Leaky fuel obviously a major fire hazard. O-ring kits are under 15 bucks- 2 rings per injector and one or more for the pressure regulator which you probably wouldn't need to mess with. My manual says to use the black/brown o-rings on specific ends of the injectors, but my kit came with all brown o-rings which is just fine. Use Vaseline on the rings to seat them. Helps you install without any damage and will get eaten away by fuel with no adverse effects.
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post #3 of 4 Old 04-26-2010, 03:49 PM
aviat0r
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Join Date: Dec 2004
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Hi, to add a little info, this jeep is a manual transmission and there is fuel pressure. He also just tried a different ECM with no luck. Seems to be getting fuel just not igniting it.

Any other ideas?
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post #4 of 4 Old 04-27-2010, 04:30 PM Thread Starter
mike13
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1990 XJ Cherokee 
 
Join Date: Apr 2010
Location: Arvada,Co
Posts: 2
i had it towed to a shop and they discovered that when i replaced the cap i was one off on the wires.runs fine now but i feel like a *******.I asked them about the spark problem and they said it was probably the crank sensor.I replaced the cap before the crank sensor so that is why it didn't start.Thanks for your help!
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