1995 Wrangle will not run - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 01-15-2007, 09:32 PM
odie
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1995 Wrangle will not run

I have a 1995 jeep wrangler 4 cylinder 5 speed. It ran fine until I went to start it. vehicle turns over with starter ok.
Can hear fuel pump in tank going on when I turn key on. sprayed starter fluid in air cleaner and it did not respond. (looked to be other problem than fuel).

I Then checked all fuses under dash and under hood. all ok.
checked to see if I have a spark to the plugs and found that I don't have spark. removed a plug and grounded it out, turn motor over and had no spark.

replaced coil and I still have no spark.

checked the wire (plug) that goes into the coil with a test light, with ignition on and with motor turning over.
the plug has two leads both showed no power.

I am at a loss can not get my jeep running now over a month
anyone have any idea where I should check next please let me know.

Thanks
Odie
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post #2 of (permalink) Old 01-15-2007, 10:28 PM
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Re: 1995 Wrangle will not run

It's broken.

Ok...so much for trying to be funny....

To be honest, you have done some logical troubleshooting....better than most people.

With out a doubt, you have determined that you have a spark problem. Once you understand how the system works, it's actually quite simple.

There are two major components that control the spark, the CPS (Crankshaft Position Sensor) and the TDC sensor (located in the dist). The CPS tells the computer exactly where the crankshaft is...the TDC tells the computer when cyl #1 is at TDC on the compression stroke...from that, the computer knows when to fire the plugs.

The most common failure is the CPS. I don't know where it is on the 2.5...on the 4.0 it's located on the drivers side of the bell housing. If you can find the sensor, try unplugging and plugging the connector. You can also use a meter to measure the resistance...if it's open, it's bad.

You have OBDII on the jeep so I would try pulling the codes before I tried anything else. Someone should be able to tell you how to do that part.

Good luck and make sure you let us know what the problem was.
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post #3 of (permalink) Old 01-16-2007, 07:08 AM
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Re: 1995 Wrangle will not run

Sounds like a CPS to me. Try pulling it off, cleaning it up a bit and plugging it back in. See if you get spark then. Sometimes the unplug, and plug back in are good for a few more starts....
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post #4 of (permalink) Old 01-16-2007, 07:16 AM
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Re: 1995 Wrangle will not run

And check the wire. It wouldn't be the first time they got melted at the exhaust manifold...
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post #5 of (permalink) Old 01-16-2007, 08:47 AM
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Re: 1995 Wrangle will not run

Everyone's giving you good advice.

Is there a check engine lamp? You should be getting a Code 11 if the CPS sensor is completely dead. If there's no check engine lamp/code then the sensor is flaky. It works sometimes, and not others. That drives a diagnostic test at a shop nuts, and leads you to spending lots of money for nothing.

The issue of no spark, no start with starting fluid, and no voltage to the coil. This points directly the TopDeadCenter (aka: CrankshaftPositionSensor) sensor. This sensor must send pulses to the computer. The computer then sees the pulses and turns on the ignition and fuel injection system. If there's no voltage on the positive side of the coil while you're cranking the engine in START mode... then you know it's about a 99.99% chance that that CPS sensor is bad.

As has been said, check it's wiring. It's not dressed too well and can migrate over to the exhaust components and melt the insulation. Then lots of bad things can happen and drive you nuts trying to find the problem.

If corrosion is built up on the pins in the connector between the CPS and the Jeep's wiring harness, then simply unplugging and plugging the connector can break down the corrosion and restore the connection. It's worth a try. If this works, fill the connectors with Dielectric Grease. It will help to keep the corrosion at bay.

Another problem is that the wiring will break internally, inside the connectors, and you'll never see it. So, if you start poking around you may restore the connection and the Jeep will start. You'll be happy, jump in the Jeep and drive away... only for it to happen again. Also, this problem will drive you nuts because there's nothing to physically see.

The CPS is located up on the top of the bellhousing.

The manual says to test:

[ QUOTE ]
Disengage the speed sensor connector from the ignition control module, then install an ohmmeter between terminals A and B as marked on the connector. The ohmmeter should read 125-275 ohms on a hot engine for 1991 vehicles and no resistance for 1992-95 vehicles. Replace the sensor if the readings are not as stated.

[/ QUOTE ]

The test usually doesn't tell you a thing...



It's really tough to get to... lots of socket extensions and U-joints and some controtions on your part and you'll get it out.

In short... Change that puppy!
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post #6 of (permalink) Old 01-21-2007, 08:08 PM
odie
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Re: 1995 Wrangle will not run

Thanks everyone its now running.
I was the CPS. I replaced it and it started right up.

thanks again for the help

Odie [img]/ubbthreads/images/graemlins/headspin.gif[/img]
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