This has been on-going for awhile now, but it's gotten to the point where it's unusable to me.

Spark is intermittent, for some unknown reason, and I've tried everything I can think of to solve the problem.

It'll start and run fine sometimes, and at others it won't hit at all. I've replaced everything (ECU, regulator, coil, magnetic pickup, cap, rotor), even pulled the entire wiring harness out and rewired the ignition part of it, and nothing seems to do the trick. Can't narrow it down to any specific point in the system.

This truck came originally with the spark controlled ignition system, but now has the standard mopar ignition system. I have spare ECU, coil, regulator and pickup, and swapping these in does nothing. It's like it has a mind of it's own and runs when it wants to.

Just looking for ideas here, any suggestions appreciated.

Thanks in advance.

 

i would say if all the wiring in for the ignition system are new you may want to start looking at things like the sparkplugs and plug wires.

 

Plugs are almost new, and when it does run, it runs too smooth for there to be a problem with plugs/wires. I've tried swapping coil wires a few times, makes no difference.

I did recently have a pretty corroded battery terminal and thought it was the culprit because after I cleaned the wires and replaced the terminal it ran the next couple of times I tried it, but then after I parked it, same thing...no spark. It'll probably start again in a day or two, run fine when I move it to another spot in the drive, and next time it won't run at all. It's driving me a little nuts, honestly.

 

Since this is no longer stock please be specific when answering the questions.
1. Define "standard mopar ignition system".
2. Is it a 4 pin ECU?
3. Have you changed the carb?
4. What resister are you using and have you checked its resistance?
5. Have you checked the ASD relay? Burnt contacts can give these symptoms.
6. Is it a single or dual pick-up distributor?

 

5 pin ECU (green wire not used)
Carb is holley 600 vac. sec. Runs perfectly when it runs, fuel is always there.
Resister is factory, have a spare and affects nothing when swapped
Not even sure what the ASD relay is, the ECU is wired according to this:

http://www.mymopar.com/downloads/Ign...ystem_5pin.jpg

 

The ASD is the automatic shutdown relay. It is on the inside drivers fender just under the hood spring with the other relays. With a 5 pin setup all 5 pins are used and they only used that setup from 74-79. I would change to a 4 pin.

In either case there should be 2 wires from the ignition switch not just one. One wire hot in the start position and the other hot in the run and start position so that you get a full 12 volts during start up. The resistor needs to be bypassed like this during start up. That diagram uses the resistor during start up.

 

Here is the correct wiring diagram for a 4 pin set up. The 5 pin is numbered wrong. I will post a better 5 pin diagram.

http://www.allpar.com/fix/electronic-ignition.html

 

This is a better diagram for the 5 pin setup without the confusion. The wiring is right but the ohms reading is just wrong on this one.

http://www.slantsix.org/articles/ele...ign_wiring.htm

 

Thanks, I'll give it a try and see what happens and let you know.

 

Unfortunately, can't really do much with it right now because, of course, it decided to start and run fine today.

This is what really kills me about this thing. WHEN it decides to run, it's flawless. It starts so easy and runs so smooth, it's like it's brand new. And then, I'll shut it off and maybe a few minutes later it just won't fire at all. Plenty of fuel, just no spark. And a day or two later, when I'm over my mad, I'll go out like I did today and turn the ignition and it fires up first try.

Also, SEAL, I still don't know where that ASD relay is. The only relay I can find in that area under the hood is the starter relay. It's possible it's faulty, and I'll swap it out soon as I find one but I didn't see anything else.

I should mention, here, that I've been wrenching on my on crap all my life, and I've never, ever had a problem like this I couldn't figure out. I rebuild my own motors (just finished up a 3.1 V6, having it running perfectly in an Isuzu trooper, have the heads of 2 different saturns and will have them both up and running again soon), and I'm about as big a gearhead as anyone you've ever met, but this just has me stumped, or I wouldn't have asked for ideas from anyone. Going on 3 years now, it's been doing this. Recently, it ran great for a couple of weeks and I was actually using it again, but going down the road a couple miles from home it just died completely and wouldn't start for over an hour. Soon as it decided to fire again (and of course it ran perfectly again), I took it straight home and it hasn't left the yard since, and won't, until I can track down this problem.

Thanks for the ideas so far, soon as I can try 'em, I'll post results.

Bert