HEI Module, Bad Luck or Something Else

[rmr_69c10]

So, after running just great last weekend (and the past few months), truck wouldn't start today. Narrowed it down to no spark. Turns out the previous owner's wire that fed the BAT terminal on the HEI had come lose. So, I verify I've got 12V when switched on. Then, I plugged the connector back onto the cap (It's an MSD Streetfire 8362). Still no luck. It is possible the HEI module died while cranking it over with no power? Or just bad luck on my part? Going to remove the cap & check it all out, but bad HEI module seems most likely now.

[68c10airstream]

As a past dealer mechanic probably the most unknown/overlooked item with hei distributors is the fact in order for the module to work at all/full potential, you need to get a good ground through the base of the distributor body, through the hold down bracket, through the bolt, to intake manifold ground!!! If the distributor has the flat round gasket to prevent an oil leak coming out from under the base of the distributor it MUST get the ground as mentioned above.

I've fixed a few fresh rebuilt sbc engines with everything painted orange not starting. Cleaned the paint off of the above items and started right up!!

This info pertains to gm hei's and i assume MSD is wired the same way, not supplying a ground in the harness directly to the distributor, but i don't know for sure. Good luck!!

[rmr_69c10]

Well, got things apart and the coil and pickup coil seem to test out ok. So probably the module. However, even though it ran ok since I got it last year (although it's been mostly sitting) I did notice there is a lot of orange paint on the dizzy hold down clamp. So, to be safe I'm going to get that all cleaned up. Even though this dizzy looks pretty new, I'm sure a bad ground or less than ideal input voltage (PO had originally wired it with 16GA, which I replaced a few months back) didn't help any. Hopefully will get it going again this week sometime.

[jricharc]

I am in the same boat, it was running fine then died and wont start. I thought it was a loose wire somewhere but I can't trace that so I am thinking the module was going in and out of commission. Let me know what you do to get yours running again!

[El Dorado Jim]

sub'd

[rmr_69c10]

Well, just tried a new HEI module and no luck. Still no spark. I'm pretty confident the pickup coil is OK. The resistance value is within range and the connector/wires are good. So, I think in my case it may be the module and/or the main coil. I'll be getting a new coil try out soon.

I have cleaned any paint off the dizzy hold down clamp that gives me ground. And, the 12V wire feeding the dizzy is 12GA, and reading full battery voltage when the key is on. I don't have much else that would be keeping me from getting spark at this point. I will update here once I get it going. However, it will be next week. Gotta head outta town for work, so hope to get back to this next weekend. Just frustrating when it was running so well a couple weeks ago.

[rmr_69c10]

Some additional testing tonight revealed my battery is a bit weak, 11.6V. But, when cranking the BAT lead to the HEI dropped down to around 9.5V. From what I've read, that may be too low to get the module to kick on and tell the coil to fire. Maybe things were working before because that battery had enough juice left to keep it closer to 11V on the BAT lead when cranking? Going to spend some more time on the wiring and get the battery charged back up. Want to make sure that BAT lead is getting near 12V when I try to fire it up.

[rmr_69c10]

Replaced the module and coil (and cap & rotor for good measure) and it fired right up. So, to summarize... I had the old module tested and it was for sure bad. Just replacing the module with a new one that tested good did not fix it. So, I got a new coil as well. That seemed to do the trick (in addition to making sure all the wiring is good). My best guess is the old too small wiring did in the module and coil over time. Anyway, need to get the timing dialed in again but it's running