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Old 06-11-2011, 07:51 PM   #1
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Why won't it start.....but then it does?

I'm troubleshooting a problem I'm having but it only happens every once-in-a-while. It's a '91 Wrangler, 4.0 liter.

Three times now, it has failed to start but cranks good, appears to be firing good, but acts like it's not getting fuel. (It will run on ether) Yesterday it was towed home because it wouldn't start but after sitting in the driveway a half hour later it started fine. This morning it started fine.

Before I drop the tank and get into that, I want to investigate other possibilities. I've heard some about ignition module problems.....could this be a starting point? Thanks!

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Old 06-11-2011, 07:57 PM   #2
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do you have an aftermarket alarm?

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Old 06-11-2011, 07:59 PM   #3
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Quote:
Originally Posted by ilyes View Post
do you have an aftermarket alarm?
No, no after-market alarms.
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Old 06-12-2011, 01:42 AM   #4
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If it was ignition problems it would not run on ether. You have a fuel delivery problem. Check to see if you are getting pressure to the fuel rail when the problem is present.
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Old 06-12-2011, 09:43 AM   #5
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I had this Same problem for two weeks if I shot it with ether it would start and run fine but would not start on it's own and I've been asking people what the piece is called and no one has answered the thread is called recommended plugs if you read you'll understand why the thread started off called that way. Anyways there's a picture there it's a little switch screwed to the side of the intake and everytime the jeep goes to full throttle the linkage hits this switch and the switch gets stuck in when it's suppose to come back out after the throttle goes back to normal position. I'm not saying that's your problem but it's worth checking. Mine when I lift the tab off the button my jeep starts on it's own.
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Old 06-12-2011, 05:45 PM   #6
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do you smell a strong gas smell and also when it dies goin down the road is it hitting real hard then backfiring and then dying? If so mine did that last week. I changed my coil, sparkplugs, plug wires, distributor cap, and distributor button and it fixed the problem. I thought it was a fuel problem because of the strong gas smell and when it died on me it acted like it wasn't getting fuel. It was very misleading with the symptoms.
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Old 06-12-2011, 11:13 PM   #7
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It could also be an air problem. Clean your throttle body and specifically the Idle Air Control (IAC) Motor. The IAC is that little box on the side of your throttle body that has a plug to it. When you switch to ignition "On", it retracts a plunger inside which allows air to bypass the throttle blade (which is closed). These plungers can stick closed which will starve the engine for air at start up.
Also, next time it fails to start, locate the pressure release valve on the fuel rail. (It looks like a tire air valve & will have a plastic cap on it.) Stuff a rag under it and vent the pressure using a small screw driver or a key. If fuel squirts out then you do not have a fuel delivery problem.
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Old 06-13-2011, 11:12 PM   #8
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Next time you have this issue turn the key to the run position and look for the check engine light. If you have no check engine light then you have a ecm problem that can be fixed if you can use a soldering iron.

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