My car used to start...

[Sue]

Well it sometimes starts, but rarely. I thought I had solved the problem when I sent my MSD 6al in to get the caps replaced but when I but the box back in my car, it still either doesn't run or starts and then dies. I hooked up a timing light and got the car to start but then the light stopped flashing and then, of course the car stopped running.

I thought it was a bad cap in the ignition box because I had eliminated the power/grounds but continued to have an inconsistent problem where the car would start and randomly it would die but then run fine for days. All this seemed consistent with a problem in the ignition box.

I know I have inconsistent spark but I’m out of ideas. I have checked the ground, power, traced all wire to/from the ignition box, sent the box into MSD for repair, checked the dist. (looks to have been firing)...

Ideas...
:banghead:

[matty b]

what type of coil are you running? I had this issue with an MSD blaster coil that was mounted horizontally. These are oil filled and after a couple minutes if the oil isnt bathing the windings it will over heat and stop firing. If you look at the instructions it tells you not to mount it like that but it is in very small letters. IF in fact you have an oil filled coil that is mounted like that, get a new one and either mount it upright or get an epoxy filled one like the black blaster coil and yoy can mount it front ways, side ways back ways. This is just one possibilty maybe itll help.

[Sue]

Thanks for the help but unfortunately I'm using an HEI dist. with the coil in the cap.
I have to be missing something?!

[70bird]

Maybe dis-connect MSD box from system to rule it out. If it runs fine without it will have at least narrowed your problem down to wiring or the box itself. Worth a try IMO
-MArk

[David Pozzi]

Connect a test light to the "Tach" terminal and crank it with key on. Ground the other end. The light should flicker but not go completely out like it would with a point ign.
If there is no flicker, the pickup coil is probably bad. They are often temperature sensitive.
David

[Vegas69]

You can also do an AC voltage test on your pick up coil. You simply hook up your volt meter to each terminal and turn over the engine to take the measurment. MSD should have the spec, if not GM has a spec for there HEI's.

[Sue]

Thanks a lot guys! First i'll try the light as it seems easiest and narrows it down - i'll let you know how that turns out.
Since i've had the msd box, i haven't hooked up a tach. Do i need to get a 'tach filter' for the light to work?

[Sue]

So i went out to hook up a light.
But first i had to reconnect the grounds because of what i was trying before. I reconnected everything and it started right up!!
The only thing i can figure is that it was originally the box and when i reinstalled it i didn't ground it properly. Whatever the problem, i couldn't be more happy i'm driving it again.
Thanks for your help guys!

[zbugger]

How do you have the box hooked up to the distributor? Are you running it through the factory module? Also, HEI's are known for an overheating coil which causes a problem with dying after a while, and being able to start after it cools off.