Renix starting issues
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Plugs are the wrong brand and appear worn out. Replace them with NGKs gapped at .035"..
No need for dielectric grease on the connectors. Just get them clean.
No need for dielectric grease on the connectors. Just get them clean.
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Plugs over 55 might well cause problems. I don't see anything alarming on the deposits. You can re-gap the new NGK's when THEY get up above 35. (all of our gaps are a little bigger with each mile)
Since I have little clips on my meter, I can check my CPS in less time than it takes me to type: "Since I have little clips on my meter, I can check my cps in less time than it takes me to type"
In my sig is a writeup Cruiser did on that. A nice one to know/rule out.
Since I have little clips on my meter, I can check my CPS in less time than it takes me to type: "Since I have little clips on my meter, I can check my cps in less time than it takes me to type"
In my sig is a writeup Cruiser did on that. A nice one to know/rule out.
Thread Starter
CF Veteran
Joined: May 2011
Posts: 1,458
Likes: 2
From: Glendale,Az
Year: 1990
Model: Cherokee
Engine: 4.0l 6Cyl
Originally Posted by NorCalJeep
Think it would be cheaper and better in the long run to buy new plugs.
Thread Starter
CF Veteran
Joined: May 2011
Posts: 1,458
Likes: 2
From: Glendale,Az
Year: 1990
Model: Cherokee
Engine: 4.0l 6Cyl
OK guys, well back to the same problem I started with.
I got off work Friday at 8. Parked the jeep by 8:30, did not touch it till about 10pm Saturday and what do you know my old problem came back. It will crank and crank and not start.
I replaced all this stuff in the past month:
Zj clutch fan
Spark plugs
Cap
Rotor
Fuel filter
Iv got fuel in the rail, I can hear the pump working away while cranking. I'm assuming I have spark because this issue is off an on so randomly.
When I dump a cup of fuel down the throttle body it acts like it wants to start but nothing.........
Here is a coincidence also, the weather is very humid due to a storm like last time I had my issues. I don't know if its actually affecting this but its very similar. What do you all think.
Oh by the way I currently have a completely full tank of gas so the pickup should be sitting in fuel right now.
I got off work Friday at 8. Parked the jeep by 8:30, did not touch it till about 10pm Saturday and what do you know my old problem came back. It will crank and crank and not start.
I replaced all this stuff in the past month:
Zj clutch fan
Spark plugs
Cap
Rotor
Fuel filter
Iv got fuel in the rail, I can hear the pump working away while cranking. I'm assuming I have spark because this issue is off an on so randomly.
When I dump a cup of fuel down the throttle body it acts like it wants to start but nothing.........
Here is a coincidence also, the weather is very humid due to a storm like last time I had my issues. I don't know if its actually affecting this but its very similar. What do you all think.
Oh by the way I currently have a completely full tank of gas so the pickup should be sitting in fuel right now.
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Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Try this:
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 it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 11-29-2011
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 it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 11-29-2011
Thread Starter
CF Veteran
Joined: May 2011
Posts: 1,458
Likes: 2
From: Glendale,Az
Year: 1990
Model: Cherokee
Engine: 4.0l 6Cyl
Originally Posted by cruiser54
Try this:
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 it's mounting holes with the first drill bit that just won't fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 11-29-2011
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 it's mounting holes with the first drill bit that just won't fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 11-29-2011
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Thread Starter
CF Veteran
Joined: May 2011
Posts: 1,458
Likes: 2
From: Glendale,Az
Year: 1990
Model: Cherokee
Engine: 4.0l 6Cyl
Originally Posted by cruiser54
Possibly. Check the cPS output and you'll know for sure.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Thread Starter
CF Veteran
Joined: May 2011
Posts: 1,458
Likes: 2
From: Glendale,Az
Year: 1990
Model: Cherokee
Engine: 4.0l 6Cyl
Originally Posted by cruiser54
Bottom and it's a bit of a *****. Check it first.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Why aren't you testing yours first??????????
Member
Joined: Mar 2012
Posts: 187
Likes: 0
From: Las Vegas, Nevada
Year: 1990
Model: Cherokee
Engine: 4.0L 6Cyl L8
Originally Posted by tjwalker
You don't need mud to foul it. The crank sensor is a common fail for any 4.0 engine.
Test it. Here's how.
-----------------------------------------------------
Renix (87-90) Crankshaft Position Sensor 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 crank sensor directly from the Jeep dealer for best reliability and longevity.
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 it's mounting holes with the first drill bit that just won't fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Test it. Here's how.
-----------------------------------------------------
Renix (87-90) Crankshaft Position Sensor 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 crank sensor directly from the Jeep dealer for best reliability and longevity.
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 it's mounting holes with the first drill bit that just won't fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.