Anyone have "overheating" issues with MSD dizzy (8579)?

[mgb0302]

I have a complete MSD ignition system (6AL box and 8579 Pro Billet dizzy). Other engine details are: MSD atomic EFI (external fuel pump) on a stock 302. On hot days, after driving the Bronco for awhile, it sometimes will not start after I shut it off. I have a couple of friends that say they have read that the magnetic pick up inside the dizzy sometimes over heats and does not operate correctly. So the first time it did not start back up, I opened the hood for a quick look, tried to start it and it fired right up. This has happened several times now and the cure is always to just pop the hood for a few seconds; I assume the dizzy is over heated (due to being stopped and sitting on top of a hot engine with no cooling) and the rush of cooler air after opening the hood cures it. Unsure if this is just coincidence or not but it makes logical sense. Any thoughts?

 

[bronconut73]

And you have ruled out vapor lock?

 

[pcf_mark]

Next time it happens see if you have spark at the plug wire. The only time I have seen heat impact an MSD is when someone mounts the box on the fender next to the headers. Then they just plane die.

I'm going with vapor lock. If you cycle the key several times letting the fuel pump re-prime each time I get it is much better / starts right up.

 

[ntsqd]

The inductive pick-up and the reluctor used by MSD are the same parts used in Ford's Dura-Spark II (or were until MSD started making billet reluctors). Can't say that I've ever heard of these having the problem that you're describing.

I'm going with MSD box malfunction or vapor lock.

 

[SHX669]

I had that issue with a DurasparkII dizzy - turned out to be the "magnetic pickup " . There's a test of resistance or something you can make - i don't recall off hand what it is though.

 

[mgb0302]

thanks

Thanks for the info. I have not ruled out vapor lock, Is there a way to actually test for that?

 

[DirtDonk]

It's very unlikely that you have vapor lock with your Atomic EFI, but just to be sure, are you running a return line setup? Without the return line, your fuel can still heat up. But it's still not as likely an issue as it would be with an engine mounted pump and a carburetor.

It's also unlikely that just a few seconds to a minute of cooling effect is going to make an overheated distributor work again.
Unfortunately...

That said, it neither can be conclusively ruled out yet. Just looking less and less likely.
If the magnetic pickup thingies are just barely at their breaking point (that's distributor humor, ar ar ar...) then I suppose this could be possible. Just never heard of anything cooling off that quickly short of dousing it in cold water.

It is hard to argue with consistent results like yours of course. Just that they seem so abnormal even for a Bronco!
How's the rest of your electrical system and have you measured the fuel pressure during these times yet?

Good luck.

Paul

 

[mgb0302]

reply

Paul,

Good advice with the fuel pressure check. ill do that
I am not running a return line. I did order a new tank with internal pump yesterday so maybe that will help. Will try it for a while before I spend the extra 300 on a return line system.

Thanks
Mike

 

[gunnibronco]

I ran a MSD dizzy for years (don't remember the model number). I had random failures that were very difficult to diagnose. I ended up letting it idle till if finally died. Maybe 30 minutes or longer. When it failed, the dizzy didn't send the pulse to the MSD 6 box. There was a troubleshooting description I found on MSD's website that described the testing procedure. It was the magnetic pick up, under the rotor that was randomly failing, usually when hot. It would take longer than you describe to cool off and restart.