87 XJ Won't start
09-01-2013, 10:23 PM
#1
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Year: 1987
Model: Cherokee
Engine: 4.0L rebuilt, head work, 703 injectors
87 XJ Won't start
New AX-15, 2 new CPS year of the engine not the tranny, new flywheel everyone says it can only go on one way because of bolt pattern and its the year of the engine , new frame grounds, new cap yes the wires are right, new rotor, have fuel at the rail, tested the coil a little below the OHMS in the book but no one says about how low it can be but no spark from there has voltage to it. The engine is not very old and never had any problems with it starting before the AX-15 swap, I only unhooked the transfer case plug, reverse lights and CPS so how did I get this lucky? Been working on getting it going for two months and I'm lost at this point have gone over all kinds of post and still nothing. 
09-02-2013, 07:22 AM
#4
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Test the CPS output. Here's how:
Renix CPS Testing and Adjusting
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 01-26-2013
Renix CPS Testing and Adjusting
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 01-26-2013
09-02-2013, 08:31 AM
#5
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Engine: 4.0L rebuilt, head work, 703 injectors
09-02-2013, 08:37 AM
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Yes because the first one they sold me I caught that it was not the right one so I had to take it back and order the exact one and I matched up the second one with the old one and the bolt holes only go one way from what I can tell two are different
09-02-2013, 08:42 AM
#7
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Year: 1987
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Engine: 4.0L rebuilt, head work, 703 injectors
Test the CPS output. Here's how:
Adjusting
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
[/B][/SIZE][/FONT][/SIZE][/FONT]
Revised 01-26-2013
Adjusting
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
[/B][/SIZE][/FONT][/SIZE][/FONT]
Revised 01-26-2013
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09-02-2013, 08:59 AM
#8
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Year: 1990
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We know the flywheels only bolt to the crankshaft one way.
The issue is that the early and late flywheels have different "trigger teeth" for the CPS and are not interchangeable as a result.
The issue is that the early and late flywheels have different "trigger teeth" for the CPS and are not interchangeable as a result.
09-02-2013, 09:21 AM
#9
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Ok just saying some people keep telling me to pull the tranny to make sure the flywheel is on right. I have .69 to .71 each time I try the CPS test never below .5, ohms are 216
09-02-2013, 09:25 AM
#10
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My concern is that possibly you don't have the flywheel to match your original engine.
Although, you have quite high CPS voltages. On the AC scale, right?
09-02-2013, 10:03 AM
#11
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Yes it is on the A/C setting and I'm using my fluke 87 meter I just called them and they checked the flywheel part # and said its for this 87 year model jeep.
09-02-2013, 10:08 AM
#12
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When the CPS is plugged in to the jeep it seems to bog down with fuel and has a little hick up to it at times
09-02-2013, 10:10 AM
#13
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The fire wall ground was also getting hot when I first started trying to start it back up that's why I added more grounds from the engine to the frame also.
09-02-2013, 01:15 PM
#15
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Year: 1987
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