Chevy & GMC Vans

My 305 89 Astro has begun to have a problem that baffles me. When cold, it always starts right up, but once it's come up to temperture and I shut it off, it can have problems starting again. It cranks just fine, but acts like there's no spark. It did it to me about a week ago at the lumberyard: crank, but no start. I could see there was fuel in the bowls by sighting through the bowl windows. I ended up removing the engine cover and checking all the wiring connections from the HEI distributor and the MSD 6A ignition module. All seemed well, I could find nothing wrong. I decided to attempt starting the engine one last time before calling a tow truck. I scarcely bumped the starter and the engine was idling like nothing was ever wrong.

Has anybody ever had an MSD 6A ignition module go bad? If so, did it get intermittant first or just die all together?

total shot in the dark... other than idling just fine once you get it going it seems like 2 vehicles i've experience coolant temp sensor issues with.

Robby's engine isn't 'puter controlled, Crash. I think Rob's on the right track with a possible faulty ignition component

what else do you expect being that it's dark up here 24/7 ?

like I said.. shot in the dark

did you say there was fuel in the bowls???
is your van carburated???

there's your problem. it's 2007 man, get some fuel injection.

but seriously,
It sounds like the MSD unit is bad. Take it off and put the ignition back to stock. If it fixes the problem, junk the MSD garbage and get a CRANE setup.
My friends and I used to run MSD boxes in the 90's and they would constantly break. We would have to ship them back to MSD and they would fix them for free but it started to become a PITA. I think my friend's mustang STILL has the Crane box that we installed when we were teenagers (10 years ago).

Ryan, I have considered putting back in the HEI parts to see if it stops the problem, but the trouble is so intermittant that I don't know how long it would take to see if it helped.

I started with EFI on this engine, but switched to a carb when I realized that the ECM couldn't handle the changes made to the engine during the rebuild (cam and compression ratio). I have nothing against fuel injection; it's great, actually. But there's something elegant about how a carburetor does its job, too. I especially like being able to dial in a carb by making jet changes, just a few hand tools needed to do that. I use computers all day long at work and I weary of them, so it's nice to be able to tune things without a computer getting in the way.
Also, I began driving in 1968, so I've got a lot more miles with carbs than EFI. Not a big deal, but carbs are more familiar to me. 'Course, it's probably just my age showing with its corresponding resistance to change.
Besides, there just isn't a sound out there like that of a V8 when the secondaries open on a 4 barrel.

Rob,,haven't had that problem with my MSD yet and hope not. A few questions,,have you changed any of your battery cables or relocated your battery and if so, what size cables did you run ?
Didn't you have a carb spacer on your other carb ? Did you use it on the Demon ?

Larry,
Strange you should post on this thread just now...Last night the no-start problem happened again, but this time the engine wasn't warm. Once again I was wondering what to do next when I tweaked the MSD timing control knob and advanced the timing a hair. I cranked the engine one more time and it started immediately. Is there a dead spot in the MSD timing control or was it just a coincidence? I don't know, I can't make it fail again. I've got to find a way to monitor the two ignition boxes to see if I can track this down.

I'm using aCometic spacer/gasket between the carb and the intake manifold. I had to get the length of the air cleaner threaded rod just right so I could get the air cleaner off; there's not much clearance room for that in the engine bay.

I haven't relocated the battery yet--think I'll wait for warmer weather before I do much to the van.

Well,,ya got fuel and I assume spark so gots to be in the box or your inside timing control but I don't think it would be the control box unless it has a short there at some point. Now it's done its thing when cold so that rules out the cable issue I was thinking about and also hot fuel.
Think what I'd do first is go through evey inch of wiring from the dist. to MSD to Timing contol box and see if there's anything there and my guess is you've already checked all your grounds, right ? I have several grounds but the one bolted to front of block gave me the same problem you're having, it would crank fine and then later, hot or cold it would turn over but would not crank. Traced everything I could think of and after the 4th time checking all grounds but this time I ran my hand all the way down to the block instead of eyeballing it. Turns out that ground had a broken end and looking at it, it looked fine but when I pulled the cable it was not connected to the block. At times it had enough ground to crank and other times enough to turn over but not crank.
Let me know how it goes.

I haven't had the no-start problem for about two months now. About then I removed the distributor cap and noticed a sparse powder deposited around the interior of the top of the cap. There wasn't much there actually, but I wiped it out and haven't had a starting problem since. Not sure what the powder was, but the brass contacts in the cap were worn a bit, as was the rotor tip. I replaced the cap and rotor last week due to this wear.
Could the intermittent problem have been as simple as that? I would have thought if the the powder was the problem, the van wouldn't have ever started. Don't understand it, but all seems well now.

My son's super duper modified 91 Camero had intermittant ignition problems. Turned out to be the pickup coil for the magnetic star. Mainly would stop running when it got hot. Would start almost everytime when cold.

Keep us posted......