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Unread 11-25-2010, 11:58 AM   #1
Matt The Hammer
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1995 YJ Wrangler 
 
Join Date: Oct 2007
Location: Westville, NJ
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Bad CPS Symptoms?

I can't get my YJ to start.

I have between 31 and 38psi at the fuel rail. Holds pressure fine after I try starting the Jeep too.

Replaced the fuel filter, dist cap, rotor, coil, wires and plugs. My ECM has been repaired (new capacitors). Engine turns but no fire.

How it ran before it died - I had two drives with the Jeep eventually dying and not restarting. Both times it started fine, ran smooth for a few minutes then stalled out once I let go of the gas. The last time, I could get it restarted twice but it wouldn't idle. After it stalled out, I couldn't get it fired again.

Searching here and the web has led me to the CPS maybe being the culprit.

Are my symptoms pointing to a new one? It's Thanksgiving, so the stores are closed. Plus, CPS are $80.

I lack a volt meter - I need to grab one - so I can't check the sensor in the Jeep (as per the FSM).

Thanks for any help.

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Unread 11-25-2010, 03:14 PM   #2
MJMPC
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Have you checked for codes?

OBDI Error/Check Engine Codes - JeepForum.com Community Jeep Wiki
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Unread 11-25-2010, 06:44 PM   #3
Jay-P
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IIRC most cps incidents involve just a sudden shutdown of the engine, not as you are describing it. Sounds as though sometimes it will run if you give it gas? Then die when you let off? How is the throttle body? Clean and free of carbon build up? Could possibly be a tps issue.

Like MJMPC said, check for codes and we can see from there.
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Unread 11-28-2010, 07:43 PM   #4
Matt The Hammer
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Thanks - No codes. That would be too easy...

I swapped in a NAPA CPS (try to stay away from the discount joints for electronics) and it's running again. $85 at NAPA.

Slight problem I found. Even with the new CPS, the engine will not run without the rotor re-installed in the dist. Doesn't matter how long you crank it, if you add starting fluid, swear at the Jeep and pray to J.

No rotor, no running. ha ha

Is the old CPS salvageable? Can they be rebuilt? The old one (197k) had an inch of crud covering it. Seems almost like it's just a magnet inside there.
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Unread 12-09-2010, 11:54 AM   #5
Matt The Hammer
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Man this CPS issue be making me nuts. At least I'm getting my money's worth from AAA towing.

Drove my Jeep with the new NAPA CPS for two weeks - no issues.

The other day I was driving home on the highway and the engine started to sputter and stall in 4th gear. I managed to run 3rd at almost 4000rpm to get me off the highway and it stalled once I pushed the clutch in and wouldn't restart.

I think the new CPS went. Is this common?

It's cold as hell outside and I have other vehicles so I haven't had a chance to tinker with it.

Any chance that the actual distributor could be suspect? I need to verify spark.

My flywheel is original. It's got 200k on it. Would that cause the CPS to not read right?
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Unread 12-09-2010, 12:23 PM   #6
Que89YJ
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No to the second CPS failing, its not common to fail twice but it does happen. Check your fault codes like MJMPC mentioned. There could be other things failing too. You need to see if you are getting spark at the plug and if you have good fuel pressure. Is you fuel pump priming when you cycle the key on?
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Unread 12-09-2010, 12:28 PM   #7
Matt The Hammer
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Just code 33 and 12. Had the battery off when I changed the CPS = code 12. The AC clutch has been throwing code 33 for 14 years.

Fuel pump is fine. Pumping 31 psi at the rail when I try to restart it.

I have to check for spark - but why would it crap out while driving in 4th gear?
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Unread 12-09-2010, 01:10 PM   #8
Que89YJ
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If its electical 4th gear doesnt have anything to do with it. There is another sensor in the distributor that could be bad (The distributor pickup sensor) or maybe even something as a bad coil. If it is dead then you just need to see what the symptoms are and where they take you. Do you have spark? Does the fuel pump prime? What faults are present? and What is the Fuel pressure? You answered the last 2 so if you answer the first 2 we can point you in a direction to get it running.
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Unread 12-09-2010, 02:06 PM   #9
Matt The Hammer
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Thanks for responding.

Ok, I'll check for spark when I get a chance.

I was going to replace the dist. and even tried to remove it. After working on the hold down bolt for too long, I just returned the dist back to the store and told the employee that removal was impossible with the engine in the Jeep. He then showed me the distributor bolt removal tool they sold.

Looks like I may be using this tool now.

Replaced the coil about a year and a half ago with an Accel model. Also did the 'brain surgery' then too on the ECM. ECM seems to be ok still as the CEL does come on.
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Unread 10-30-2011, 01:44 PM   #10
sdg3205
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My 2000 TJ is on its 3rd CPS. I can now tell when the current one is on it's way out. The engine will crank for longer and longer until it fires up. Eventually it just stops firing up altogether.

The first time it died was in 2004. It was sudden then and the odometer read "No Buss". I had a dealership fix it, and they did a terrible job (I wont get into it now) and it ran poorly for a few months at which point it was serviced and fixed correctly.

My fathers 1994 Cherokee ran over 200K miles with no CPS issues.

Why am I burning through these things?
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Unread 10-31-2011, 05:39 AM   #11
Que89YJ
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Wrong forum. It sounds like the first issue wasn't the cps at all. Cps's don't fail that often, but the after market stuff that we have been seeing here is causing many people issues with bad out of box and high failure rates.
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