No Spark condition

[Top C]

I hope I'm in the right area to to ask this question.

My 87 MJ 4.0 has no spark. I did the following checks

 

Took the center wire off the distributor cap and put spark plug on it and no spark

Cleaned the C101 connector no spark

Unplugged the CPS cable and reconnected it no spark

Unplugged and reconnect both connectors on the coil no spark

Check the relays all are good

 

So my next thought is replacing the CPS Sensor is Napa the best place to purchase?

Should I next look at the Coil and the unit the coil sits on?

The last item would be ECU I replace the original 5 yrs ago with a 90 ECU but kept the original if all else fails I will put that back in.

 

Since I know this is an electrical problem and I've isolated the distributor from the problem is there anything else I'm missing should be check that would cause a no spark condition?

Thanks

Mike   

 

[eaglescout526]

Have you tested the CPS to make sure it is outputting more than .02 VAC?

[Top C]

No I have not retested the cps. I heard different options about this. Is .02 VAC the minimum  you want to see on the CPS? Does the engine need to be cranking to measure the voltage?

Thanks for your reply

Mike

[eaglescout526]

Yes, its pretty easy to stick the leads in the connector and see what it is outputting while cranking. .02VAC is the absolute bare minimum but honestly, dont settle for that. Factory Siemens/Renix CPS output .05VAC with .03VAC being the lowest. Shoot for something that will do .03VAC.

[Top C]

Ok thanks that clears up the confusion i had about this. I will give it try tomorrow evening and let you know I find.

[Top C]

Okay so I test everything that is check for 12vdc at the larger of the two ports on passenger side and got 12v. Then went to the ECU and got 12vdc there using the cable ground, so I was checking both positive and negative at cable connector. Then I check for 05 ac at the EUC nothing (engine cracking). Then I went the CPS and check there for .05 Vac nothing there. So I pull the CPS sensor and will replace it. It will probably be Thursday afternoon before I can get to it. Those bolts holding that sensor are a real pain to get to. Luckily they were not  rust in. I think I'm going to get one bolt  in on the CPS, get the engine start and drive it to my friends garage have them put that second bolt in. My luck I'd drop it through the slot into bellhousing. 

Thanks for your help I'll report back after I get it running.   

Mike

[eaglescout526]

11mm and a lot of extensions work too. Just make sure you don’t lose the bolts. They’re special. 

[Top C]

Update got the new CPS installed this evening and engine started right up. Thanks to all the comments and suggestions. One thing I found very useful was a swivel socket my bolts were 7/16 and my friend had one. 10 mins tops to reinstall with it. If you have an automatic you need to unbolt the bracket holding the shifter cable makes that much easier.

Thanks again keep on Jeepin!

[zomeizter]

10 hours ago, Top C said:

Update got the new CPS installed this evening and engine started right up. Thanks to all the comments and suggestions. One thing I found very useful was a swivel socket my bolts were 7/16 and my friend had one. 10 mins tops to reinstall with it. If you have an automatic you need to unbolt the bracket holding the shifter cable makes that much easier.

Thanks again keep on Jeepin!

nicely done!