Novak Conversions Jeep Wrangler YJ shifters

YJ cranks but does not get spark

J

Jacope01

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Joined
Oct 28, 2024
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6
Location
Kentucky
My 95 YJ (4.0) has been sitting for a couple months now due to this issue.

I believe that I’m not getting power coming into the ignition coil with the key in the “On” position.

I’ve chased my tail up to this point. Lots of stuff has already been replaced.
Maybe I’m checking power into the coil incorrectly? Jeep will crank strong and almost turn over but no power (I assume) to the ignition coil means no spark which means no start.
Check all fuses in cab and in engine bay and they all seem good.
This is my first vehicle and I’m not super experienced with wiring so it’s been a struggle tracking down what is wrong.

Thanks!
 
There are some basic trouble shooting videos on Youtube that should help walk you through some diagnosing procedures. Power addicts channel and jeep solid channel are two I recommend.

First, when you first turn the key (just a couple of clicks, but not cranking) do you see the Check engine light come on? That is the very first thing you should look for. that is the PCM self test light. If it doesn't illuminate, make sure the bulb is good. if it still doesn't illuminate, that is the sign of a failed PCM.

If it passes that, swap out some relays in the box under the hood. You need to swap your ASD (Auto shutdown) relay with horn or something insignificant to engine functions.

if it still doesn't start, listen to see if your fuel pump will turn on. Just turn the key a couple of clicks, but don't start motor. Listen for the little hum at the rear of the Jeep. Note, after a couple of starting attempts, it may not turn on since it will have primed. There will be youtube clips on how to bypass the relay to give it full time power to test. Power addicts channel.

If it comes on via bypassing relays, then do the relay swap again with the horn relay and the fuel pump relay. See if it fires or not.

If it passes those tests, but still doesn't start, look up fuel pump/fuel pressure testing on Jeep Solid channel again on how to check for fuel getting to throttle body.

Do those tests and report back.

I had an issue recently with mine dying during a drive, then not having fuel pressure at all to the fuel rail, but pump was turning on. Turned out the replacement pump/sender in the tank developed a split in the short rubber pick up tube.

There are other things (sensors) that can also cause non-starting issues. All in all, these things are pretty basic, so a good vehicle for you to 'cut your teeth' learning how to troubleshoot and do repairs on. Good luck!
 
Also, if the computer self test passes, do the code check on the pcm as well. Jeep solid should also show how to do the obd 1 self test.
 
dodgerammit said:
There are some basic trouble shooting videos on Youtube that should help walk you through some diagnosing procedures. Power addicts channel and jeep solid channel are two I recommend.

First, when you first turn the key (just a couple of clicks, but not cranking) do you see the Check engine light come on? That is the very first thing you should look for. that is the PCM self test light. If it doesn't illuminate, make sure the bulb is good. if it still doesn't illuminate, that is the sign of a failed PCM.

If it passes that, swap out some relays in the box under the hood. You need to swap your ASD (Auto shutdown) relay with horn or something insignificant to engine functions.

if it still doesn't start, listen to see if your fuel pump will turn on. Just turn the key a couple of clicks, but don't start motor. Listen for the little hum at the rear of the Jeep. Note, after a couple of starting attempts, it may not turn on since it will have primed. There will be youtube clips on how to bypass the relay to give it full time power to test. Power addicts channel.

If it comes on via bypassing relays, then do the relay swap again with the horn relay and the fuel pump relay. See if it fires or not.

If it passes those tests, but still doesn't start, look up fuel pump/fuel pressure testing on Jeep Solid channel again on how to check for fuel getting to throttle body.

Do those tests and report back.

I had an issue recently with mine dying during a drive, then not having fuel pressure at all to the fuel rail, but pump was turning on. Turned out the replacement pump/sender in the tank developed a split in the short rubber pick up tube.

There are other things (sensors) that can also cause non-starting issues. All in all, these things are pretty basic, so a good vehicle for you to 'cut your teeth' learning how to troubleshoot and do repairs on. Good luck!
Click to expand...

Hey man. I’ve been tooling around with it on and off. I had replaced the CPS but I just ohm tested it while disconnected and it was pulling 15.5k Ohms off pins B and C. That is way higher than what I think it should be realistically. Would this be it?
 
Jacope01 said:
Hey man. I’ve been tooling around with it on and off. I had replaced the CPS but I just ohm tested it while disconnected and it was pulling 15.5k Ohms off pins B and C. That is way higher than what I think it should be realistically. Would this be it?
Click to expand...

I'm unsure what a good reading should be.
I take that the check engine light did illuminate when turning the key?
Also checking that you did hear fuel pump/check for fuel pressure at the rail and swap a couple of relays.
 
dodgerammit said:
I'm unsure what a good reading should be.
I take that the check engine light did illuminate when turning the key?
Also checking that you did hear fuel pump/check for fuel pressure at the rail and swap a couple of relays.
Click to expand...

CEL comes on. I can hear the fuel pump. CEL turns off after a few seconds which it’s always done. I was under the impression that a good reading is 200-1200 Ohms but could be wrong.
 
Jacope01 said:
CEL comes on. I can hear the fuel pump. CEL turns off after a few seconds which it’s always done. I was under the impression that a good reading is 200-1200 Ohms but could be wrong.
Click to expand...

Just watched a video. The person (DexJs channel) stated to have someone crank while you hold a hand on the ASD relay. You should feel the relay clicking if getting signal from CPS. Also seen others who stated most off the shelf CPS are junk and to only get the Mopar one. I have no experience there, though
 
dodgerammit said:
Just watched a video. The person (DexJs channel) stated to have someone crank while you hold a hand on the ASD relay. You should feel the relay clicking if getting signal from CPS. Also seen others who stated most off the shelf CPS are junk and to only get the Mopar one. I have no experience there, though
Click to expand...

Just tested this. No clicking at the ASD relay.
 
Hmmm. According to this video:
you don't want any reading between B and C terminals at all.
 
My jeep sounds exactly like his does when his CPS isn’t connected. I’m gonna try to find a mopar CPS. Mine is the inline three prongs that he was referencing in the video though. Thank you for your help so far.
 
So. New Mopar CPS came in today and I hooked it up + charged the battery and it sounds exactly the same. Really bummed. My RPMs don’t change when cranking. Any ideas? Fuel pressure?
 
OK....Again, Check the #5 "Dome Light" Fuse....It also controls EVERYTHING that provides what your motor needs to run.....
Fuel pump, ECM, Main automatic shut down relay. Trust me, I went through a three month swap this/that/the other thing before someone smartened me up to the #5 fuse......

 
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