Help! No spark!

[Jerry]

Looking for more advice please for my ailing red truck :)

 

Last night it was fine, come this morning, stone dead just wouldn't fire. I checked for a spark and there was none at all, not even a week one. The battery is tiptop and bursting with life, spins the motor like a good'n. So I took the car instead and tried starting the truck again later. Brrrrum! Started right off! WTF? :dunno:

 

It runs well otherwise. Not perfect but reasonably smooth.

 

Any pointers on where I could start looking for this fault? It's done the same thing once before and it wasn't sub zero and icy so I'm ruling out a temperature related problem as is often the case up here in the Great White. I checked the coil and the HT wires with a multimeter and they are fine. Shame cos that would be an easy fix!

 

Are there any ignition components or sensors that might randomly crap out like that, then just start working again? Like I said, yesterday fine this morning nothing. I didn't even look at it in between so I don't think vibration is an issue or moisture cos no rain.

 

I'm befuddled :hmm:

 

A great big TIA! :thumbsup:

[Geonovast]

Symptoms of a dying CPS. I had one go out just like that before, would occassionally cause a no-start, made the truck die while driving once, then a few weeks later completely went out.

[bgred2]

Yup, CPS is my vote, same thing happened to me.

[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

[Jerry]

Great! Thanks guys, especially Cruiser for that detailed test method.

 

So where is my CPS located then? Is it easy to get at and replace? Photo possibly?

 

Thanks again :thumbsup:

 

ComancheClub is the best most helpful place! :wrench: