Intermittent starting issues - JeepForum.com
 
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post #1 of 5 Old 07-03-2020, 11:45 AM Thread Starter
Dborns
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1984 CJ7 
 
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Location: Kansas City
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Intermittent starting issues

So about two weeks ago I was driving my ‘84, (‘96 Cherokee motor), and I got home fine. Tried to start if my later to pull it in and nothing. It was cranking but not turning over. I jumped it and it started fine. The volts were 12+. It’s been sitting in my garage since then. Yesterday, drone it around quite a bit, last errand, same thing. It wouldn’t turn over. I pushed it out into the lane to have it jumped, tried it again, and it fired right up. Got home and the battery was at 12+ volts.
I dropped the battery off at the APS to have it tested, and it’s good. What should my first move be the next time it’s dead? Have a multi-meter with me to test it right then?

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post #2 of 5 Old 07-03-2020, 11:47 AM Thread Starter
Dborns
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1984 CJ7 
 
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Sorry for the typos, I know how to spell, autocorrect sucks
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post #3 of 5 Old 07-03-2020, 02:15 PM
pedal2themetai
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HI Cranking and turning over are the same thing... if the motor was spinning it was cranking (turning over) .. Now do you mean the starter was spining but the motor was not? or it was cranking but not starting? Need to clarify that first..
good luck
tim
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post #4 of 5 Old 07-03-2020, 05:17 PM
LumpyGrits
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Ck the starter motor

Have'n you along, is like loose'n 2 good men
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post #5 of 5 Old 07-03-2020, 09:35 PM
BagusJeep
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Volts at 12+ are just showing you battery voltage. You need 13.5 -14V to charge the battery properly, that is the job of the alternator. On your engine the alternator was controlled originally by the PCM, is it still so?

I have a lot of these issues on my fleet so I spent $40 on a proper battery tester. It is a voltmeter with a carbon resistor. teh resistor mimics the load of starting when I press the test switch. I am looking for a 12V battery to not dip below 10.5V after 8 seconds. This means it is going to provide enough current to drive the starter motor. When the engine starts the voltmeter then shows me if the charging system is working. A good gadget that does not need AA batteries, it sits on the shelf until I have an issue like this.


It may be that you also have an internal motor problem. In the motor are four carbon brushes in sprung loaded holders that push on to the commutator. They can seize and then not make contact. If you are down to two working ones, it will turn slowly and you will need more current to get the engine started. They are very simple devices and a starter can be stripped using a screwdriver and spanners in a few minutes. The brushes can be inspected and freed, the whole lot greased and back together in under an hour. Access is good under a Jeep!!!


Why are these related? When you jump the battery you are connecting to a working alternator and battery that will probably boost your cranking volts from 10.5 to 12.5, even 13V. There is a lot more current to drive a starter that needs more current to move at the right speed. Maybe I am not right in this case but if the battery and solenoid are fine I always start to think about the starter motor, and being able to start the engine with a shed load more power behind the battery does not mean teh starter is fine.


so you need to troubleshoot a little more, measuring voltages at the battery when it is sitting, when you are starting and when it is running. 12V should go down to about 10.5V when starting and back up to about 13.5V if all is well.

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1981 CJ7 258ci - Bagusjeep
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