Ran great then one morning won't start

[alpha6]

First off...thanks very much to BusaDave9 who has posted so much regarding this problem. If you haven't read it, go here. http://www.jeep-cj.com/forums/f99/engine-wont-start-troubleshooting-guide-19494/

Dave recommended that I start a new post as I went through the problem which was my jeep was running great then one morning it just wouldn't run. Starter would turn, fuel to carb, but wouldn't catch. I quickly ran through the checks recommended by Dave and have narrowed it down to the ignition system (I think). I wasn't getting any juice on solenoid so I replaced that. ($14 bucks at O'Riley - it looked like the original one anyhow.) I now have juice going to the "i" terminal and when I pull the plug on the "s" terminal and check inside it I am getting 12 volts when the key is in "run". The problem is that there is still no juice on the positive side of the coil.

So what now? The coil is newish, as is the cap. I have a light on the MSD.

 

[Tin Medic]

Any melted wires or loose connections? With a new solenoid I would think a wiring issue somewhere.

 

[alpha6]

Nope...I traced all the wires...all looks good. Keep those suggestions coming.

 

[Tin Medic]

Was it acting funny yesterday?

 

[Tin Medic]

What type of coil? Do you have a different one you can try?

 

[Tin Medic]

I have a spare MSD Blaster 2 coil if you want to go that route, yours if you want it.

 

[alpha6]

That's what I have on it. When I put in the MSD I put in the new Blaster coil. Thanks Tin Medic.

 

[Tin Medic]

Its possible the coil is bad also. Strange that the coil and solenoid would go at the same time but anything is possible.

 

[IOPort51]

I think there is a hall effect coil in the distributor that can mess up as well

 

[alpha6]

Its possible the coil is bad also. Strange that the coil and solenoid would go at the same time but anything is possible.

My thought is that if the coil is bad, it should still be showing 12 volts on the positive side...I have 12 volts going into the MSR A6 and the wire that goes to the coil comes out of that...but I wouldn't think that would go bad...it's less than 6 months old.

BTW...no indication of anything amiss before it just wouldn't crank. No missing, hard starts, ran great as I said. I did try and roll start it off a hill the morning it wouldn't start...that didn't do anything but put my jeep at the bottom of the hill.

 

[BusaDave9]

Starter would turn, fuel to carb, but wouldn't catch. I quickly ran through the checks recommended by Dave and have narrowed it down to the ignition system (I think). I wasn't getting any juice on solenoid so I replaced that. ($14 bucks at O'Riley - it looked like the original one anyhow.) I now have juice going to the "i" terminal and when I pull the plug on the "s" terminal and check inside it I am getting 12 volts when the key is in "run". The problem is that there is still no juice on the positive side of the coil.

So what now? The coil is newish, as is the cap. I have a light on the MSD.

Okay so the starter cranks and cranks but the engine won't start?
That tells us the starting system is good. The starter solenoid is good.

Did you use a spark tester?

Didn't you get a spark with the spark tester? Check at least 2 spark plug wires. If you are not getting a spark we need to start our troubleshooting here: http://www.jeep-cj.com/forums/f99/engine-wont-start-troubleshooting-guide-19494/#post158741

You checked the voltage on the small wire going to the coil marked + and didn't have any voltage there? The key needs to be turned to RUN.

If you don't have voltage on the coil then the coil is not bad.

double check that you don't have voltage on the + wire of the coil when the key is set to RUN.

 

[alpha6]

I didn't check the plugs yet. Guess that is my next step. I put them and new wires in the same time I installed the MSD. In your post you said "If you don't have voltage on the coil then the coil is not bad." Did you mean it IS bad?

 

[BusaDave9]

I didn't check the plugs yet. Guess that is my next step.

No don't replace the plugs.

In your post you said "If you don't have voltage on the coil then the coil is not bad." Did you mean it IS bad?

If the coil does not have voltage it can't be expected to work. The coil is not bad.
To make an analogy: if you gave me $20 and said "go buy us some beer" and I come back without any beer. Who's fault is it we don't have beer? It's all my fault. I had everything needed to do my job.

You have tested and you don't have a spark? Correct?
You have an MSD ignition. This is important. It should be wired like this drawing:

Turn the key to RUN. Check the red wire that is coming out of the MSD ignition module going to the wire that used to go to the coil.
Do you have 12 volts there? Make 100% sure those 2 wires are connected properly.

Next Check the orange wire on the coil. This should be going to the + side of the coil. You were saying this does not have 12 volts? is that right?

 

[alpha6]

Everything is wired correctly...nothing changed from when it was running. I just doubled checked the currents. Power to the red wire from the old red coil connector. Power to the solenoid. Power light on the MSD is one. The orange wire from the MSD runs to the + on the coil. No power on the wire or the coil when it is hooked to it. I took the whole rubber adaptor off the MSD and tested the current on all the prongs coming out and there was no power to any of the prongs. I suspect something amiss in the MSD that is preventing power from getting to the orange wire.

 

[BusaDave9]

Power to the red wire from the old red coil connector. Power to the solenoid. Power light on the MSD is one. The orange wire from the MSD runs to the + on the coil. No power on the wire or the coil when it is hooked to it. I took the whole rubber adaptor off the MSD and tested the current on all the prongs coming out and there was no power to any of the prongs. I suspect something amiss in the MSD that is preventing power from getting to the orange wire.

I agree. There is something wrong with the MSD module.
That orange wire is not always 12 volts the way you would expect on an OEM ignition. I think there is something else going on but you should still call them up. MSD Ignition

Toll Free MSD Tech Line: 888-673-7859

MSD Tech Line: 915-855-7123

​

Call our tech line Monday through Friday, 7am to 5pm Mountain Standard Time
​

 

[alpha6]

Thank you sir. I will llama them in the morning. Dang it!

 

[BusaDave9]

I thought I heard something about this. Here's what MSD says"

No 12v present at Coil +

1. One common question in regards to MSD Ignition controls is “Why isn’t 12V power on the orange (COIL +) wire?”
   The main reason 12V won’t be present at coil + is because your MSD ignition is a Capacitive Discharge Ignition. Like all CD ignitions they use a large capacitor to discharge 420-480 Volts to coil + and coil – will normally be connected to ground. (That’s why you wont see +12V on coil +)
2. Most all stock ignitions are Inductive Ignitions, these will normally be connected to the + 12V ignition switch to coil + and coil – is connected to Points or the Factory Electronic Module. (That’s why you’ll see +12V on coil +)

So missing 12 volts on the coil is not an issue. Check out this link:MSD Ignition

 

[alpha6]

Soooo....turns out the box is bad. I went through the MSD testing and there is no spark when grounding the plug wire coming off the coil. So they are going to send me a new one. I am surprised that the box went bad...but I guess those things happen. Now I am thinking I need a back up coil that I can hook the old coil head too so if this happens in the woods I can hook up the old ignition system and by pass the box...at least to get home.

Mucho Gracias to BusaDave9 for his continued help and wealth of knowledge.

 

[Tin Medic]

Glad you got it figured out.

 

[BusaDave9]

Soooo....turns out the box is bad. I went through the MSD testing and there is no spark when grounding the plug wire coming off the coil. So they are going to send me a new one. I am surprised that the box went bad...but I guess those things happen. Now I am thinking I need a back up coil that I can hook the old coil head too so if this happens in the woods I can hook up the old ignition system and by pass the box...at least to get home.

Mucho Gracias to BusaDave9 for his continued help and wealth of knowledge.

Good to hear you got it fixed! Now that you have a running Jeep, are you going to be able to make it to the Jeep-CJ.com trailride in Silverton CO?

A backup coil is a good thing but your coil should still work as a backup if you can put the wiring back to factory. The biggest issue is the ignition module. With the MSD ignition module you no longer need the OEM module. Is it still installed? If so you could then wire the ignition back to factory.