was driving to work today and it shut off going 40mph, so i pull over try to crank over but all it does is crank..

the other day same thing happened to me so i changed the CPS sensor and now it happens again ( 5 days later )

i tested the old CPS and it showed .195, and also just tested the new CPS thats installed on my XJ and it reads .294

where do i start looking? i think i hear the fuel pump prime when i put turn the key on

thanks guys!!

 

I could be wrong on this, since you have a Renix and I'm no expert on those, but I think you should have 0.5?
Your CPS is adviced to be of good quality (dealer). Aftermarkets are unreliable.

 

Confirm you hear the fuel pump. Also please tell year. Idk what it's called maybe someone else will chime in but there's a ceramic plate on the drivers side towards the front that has a positive and negative connectors on it. Make sure those are on properly. Could be the reason as that is part of keeping it running after start? Check both of those. Had a problem with that this morning. But confirm those and keep posted

 

How about a 1989 2door, like in his info?
And do you mean that ceramic resistor on the driver's side fender inside? Thats related to the fuel pump, which he stated he thinks is engaging...

 

Thinking and knowing for sure are two completely different things. Sorry I didn't look at his info before replying, was just trying to help. Relax dude

 

When you test your cps, the ohms resistance is not as valid as the "ac" test. Cruiser(54) has the full procedure on how to do this. Search "Cruiser's mostly renix fixes"

 

The ceramic fuel pump resistor is not in the circuit at start up so hearing the pump prime is not an indication of the resistors condition. It is switched into the fuel pump circuit after the engine starts to reduce the voltage to the pump and therefore quiet the pump. If the Jeep starts and then dies, a failed resistor or its wiring is one suspect. If the engine won't start in the first place, it is not the fault of the resistor.

The resistor is not really needed and was eliminated on later models starting ~'95 or so. It is perfectly okay to confirm the operation of the resistor by just bypassing it (tying the two connectors together).

As a side note, the connections to the resistor are not a positive and negative -- both are positive.

 

Bingo!!

The bloke from downunder is on the right track.



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

Also make sure you routed your new CPS's wiring correctly.

 

Assuming you had good contact on a reasonable meter set on AC volts, you need to install a Napa or Mopar CPS, is my first thought.

A direct measurement, right from the un-plugged CPS should be well better than Eddited>>.35 AC Volts, (not 3.5), cranking with a good battery.

 

No worries mate, all peach and mangos here..

 

Good lord people, use your units! .195 What? .5, .294 [/rant]

 

Good luck on finding that new CPS, I was looking a few months ago for my 87 and mopar discontinued the one I thought I needed. Only two were left in CO. And the part stores were no help at all...

 

Change Your CPS; I found if you BACK the fronts onto ramps, you won't have them in the way, where you need to lay. A stand under the left front frame would be in your way.

If CPS itself is putting out less than .35 Volts AC unplugged, while it's cranking with a good battery, or the resistance is not 200 ohm's plus/minus 75, hot;

11mm socket > 3 inch extension > universal > long (18-24 inches of extension). Your feet are sticking out under the passenger side, you can reach up past the front drive-line with your left hand to hold the CPS from the front. Your right hand is on the ratchet way back by the tranny cross member. If you tie a long string on the old, you can use it to haul up the new. Toss that piece of plastic if it's still there, and do not drop the bolts in there! Echlin # CSS980, (from Napa, for 87-90), should be fine, but some prefer to go to Jeep. I wouldn't bother with anything else for that.

 

Up in post #9 I wrote 3.5 for a minimum acv from a Renix cps. Should read .35

 

update.. went to the dealer and got a Genuine CPS installed it and still no start... so i said its gotta be the coil.. went and got me a brand new coil installed it and still just cranks but no start

whats next?