Hey guys I have a 1996 jeep Cherokee country and a few weeks ago I started it and was letting it warm up then it died after a few minutes and would not start, it cranks good but has no spark. So here's all parts I've replaced... ignition coil, distributor with pickup coil sensor and cap n rotor, tested spark plug wires, cleaned all grounds, checked all relays and fuses, crankshaft position sensor, ignition switch, ecm, and cleaned the nss good and put dielectric grease in there. I'm out of ideas if anyone knows of something I've missed that would be very helpful thanks

 

When replacing sensors on a jeep use oem I have learned this the hard way. After market crank shaft and cam sensors especially and o2 sensors. I have had the same thing happen when replacing my engine put all new sensors on it, it would run but not good put my old ones on it and it ran fine.

 

1. Stop buying parts.
2. Test your ASD relay.

 

Ive heard that from other people too, I tested the voltage at the ignition coil connector and there is 10.8 volts is that the correct voltage for the ignition coil?

 

Sounds low to me but I dont know exactly what it should be I would think closer to 12v. Check your battery and see what it reads a good charged battery should read a little over 12.5v.

 

the battery is 12.35 any idea what would cause low volts to the coil?

 

There is a problem there; battery voltage should be the same as the coil B+ voltage. From your symptoms, I would guess, and it's only a guess, and you have done WAY too much guessing and parts cannon firing already, but without checking I seem to remember that the coil + is sent from the PCM. Have you pulled the diagnostic codes yet? this should have been your very first move. Then check fuel pressure, can you hear the pump prime when you turn on the key? And yes only OEM Mopar on the cks and ckps

 

Exactly. He needs to find the source of this problem.


Absolutely!!!! There has been a ton of money and time wasted here.


No, it comes from the ASD relay. The PCM pulses ground to provide the spark. Same deal as the injectors.

If the 12v were pulsed, it would be just about impossible to measure with a standard meter. You'd need an oscilloscope.

 

Yeah I know the - is pulsed from the pcm,..but what feeds the ASD relay,,ign switch? too lazy to check but that would make sense

 

ya it had the typical rear o2 sensor code I cause I dont have one. I can hear the fuel pump kick on as normal I will check the fuel pressure when I get home, are you thinking it's the cps?

 

I think you should check the fuel pressure first, because it's the logical next step.

 

ok I checked the fuel pressure and its 47 psi so that's right?

 

Your profile says you have an SJ, which ended production in 1983.?
You really replaced all these parts?? Distributor and PCM too?? No PCM in 1983.
Fyi, Its a PCM, not ECM.
It's a camshaft position sensor, not a distributor pickup coil sensor.
If it cranks and won't start, it's NOT the neutral safety switch, this just disables it from cranking, not starting.
Do you have 12v at the coil, and 5v at the tps, cts, cps, map and ckps?

 

You tell me. Does gas come out of the schrader valve when you push it in?

 

when I turn my ignition on I get 12 volts at the ignition coil for a second or two and then back to 0 and yes I do have good fuel pressure