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CPS?

Old Nov 30, 2010 | 02:40 PM
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Default CPS?

I have a 92 Cherokee with 215,000 miles. It has an intermittant starting problem.
When it does not start, the fuel pump does not run at all when the key is turned on and there is no spark.
When the fuel pump runs when the key is turned on (before the start position), I know that it will start right up.
Can this problem be caused by the CPS? Can a bad CPS turn off the fuel pump?
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Old Nov 30, 2010 | 03:23 PM
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CPS are typically good or bad.
I did have one go bad, that would work when cold then once warmed up it was dead.
You've got an electrical issue though, the fuel pump works regardless if the CPS is bad or good.
Might have a bad ignition switch.
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Old Nov 30, 2010 | 06:13 PM
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Most of the time, the fuel pump runs with a bad crank sensor, but there is one particular way in which the crank sensor fails where it can inhibit the fuel pump.

I would consider testing the crank sensor when you have these symptoms.
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Old Nov 30, 2010 | 07:33 PM
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Originally Posted by tjwalker
Most of the time, the fuel pump runs with a bad crank sensor, but there is one particular way in which the crank sensor fails where it can inhibit the fuel pump.

I would consider testing the crank sensor when you have these symptoms.
I thought a CPS was a cam pos sensor? Does this vehicle not have one? CKP is standard Yank terminology for a crank pos sensor.

Last edited by Flatlander; Nov 30, 2010 at 07:36 PM.
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Old Dec 1, 2010 | 09:44 AM
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Default Will Change CPS and Ignition Switch

I tested the CPS by checking insulation between each of the three posts on the connector. All had infinite insulation to ground and two pins were insulated from each other.
Rock Auto had a sale on the CPS and it was $30 shipped with my discount so I purchased and will put this in.
I will also put in a new ignition switch.
I would hope that between these two items it will fix this intermittant problem. It is a manual trans so I do not have to worry about the NSS.

If anyone has other thoughts please add them.
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