CPS on non-fuel-injected YJs?

[chrismik]

1041694

I have an odd problem with my 1990 YJ 4.2 ... when it gets warm (after, say 20 minutes of idling or 10-15 minutes of driving) it dies and won't restart. I get fuel, but no spark. I have seen other no-spark solutions propose a problem with the CPS, but I can't find one on my bell-housing. Are they on non-fuel-injected YJs? Also, is there a way to test the ignition control box? I am hearing that may also be a place to check. The coil, BTW, is hot, but seems OK (though, how can you know for sure) ...



Thanks,

Chris

[addsig]

 

[MudderChuck]

1041699

My numbers could be a little off, but voltage to the plus side of the coil with the ignition on, should be about six volts, and 12-14 with the motor cranking. If your getting good current to the coil and it still doesn´t spark (high voltage) it´s probably the coil (but could be the rotor or distributor cap). You didn´t say wether you tested for spark at the coil or the spark plug. A bad,dirty or wet distributor cap will interupt spark to the spark plug. Could be a bad magnetic trigger in the distributor. The magnetic trigger can be damaged with ferrous metals (screw drivers, feeler gauges and such) it´s best to check the gap with the eyeball. Checking the spark, is discouraged with most ignition modules. But sometimes you gotta do what you gotta do.

If your getting no current to the coil, it´s probably an open circuit, bad contact or broken wire, (but possibly the control module).

Can also be tested with an old lamp socket and a twelve volt bulb. Dim light with the ignition on, from the + side of the coil, to ground and bright light while cranking.

Had one distributor that quit everytime the motor got warm (winter) found a couple of teaspoons full of water in the bottom, that would turn to ice then thaw out, then coat the inside of the distributor. Jeep only ran, below 32 deg. F. now blowing out the distributor with compressed air is part of my regular service routine. Hope I´ve helped some.[addsig]

 

[chrismik]

1041704

It's not obvious from the manual I have which terminal is the positive side, but it is apparently the left (yellow) wire. The right (green) is labelled "tach test." In any event, I got about 3V with the ignition off and 12 with it on. But then again, I don't have a problem unless the car is hot. So maybe I will check again after it stalls. I am wondering, with the tach flutter I see from time to time, if the problem isn't in the Ignition Control Module or higher in the computer. But how to tell? How can you test the control module?



Thanks,

Chris

[addsig]