Hello folks I’m a bit new to these forums but I’m needing help with suggestions on finding out why my 79 Vette won’t start for me. About a week ago I was leaving for work with it and all of sudden my engine stopped, lights shut off, and radio shut off. I parked the car tried cranking and nothing no crank, eventually after testing crank the lights all came back on but still no crank. After getting off work that night I came home to check things out and now it’ll crank but no start. Here’s a list of things I’ve done…

Took off starter and alternator and had both checked, they were both good.

Changed out battery but still no start, checked both battery’s and their both good.

Found a bad wiring harness connector going to the alternator and replaced it while I was at it but still no start.

Ran a load test off the battery while I crank and I’m getting a massive drop in voltage when I crank so I know that might be part of the problem.

Checked all ground connections and they’re all good as well, some were a little gunked up and dirty but connections were good.

Checked distributor and that’s basically brand new inside and out from being changed out a long time ago.

I have heard of people bringing up a fusable link but with all the books and all the searching I’ve done I can’t find them for the life of me and the previous owners of the car at one point rewired the entire car so there’s wires cut up and not going to anything at all and all kinds of weird stuff but everything has been running great in it since I bought the car so I never questioned it much.

 

Do you own a test light? Are you getting power to that clean distributor with the key in run? Do you have a wiring schematic for your year Corvette? Do you own the Gen. GM Electrical Trouble Shooting Manual?
I would start with checking that large pink wire at the distributor for power. No power work backwards through the system. Yes power than likely a distributor problem, bad module or coil.

 

Take a close look at the upper connection of the 'starter extension harness'.

https://www.zip-corvette.com/79-w-ac...o-aux-fan.html

 

I do have a few test lights I can use and test. I don’t have the electrical trouble shooting manual probably something I oughta get now that you say that. I’m pretty sure I’m getting power to the distributor, I did notice the clip on the battery cable going to distributor is broke off and old looking so it might be a little loose if I wiggle it right. That’s the only thing I didn’t have a look at was the coil everything else looked good inside and I didn’t have any condensation built up.

 

thanks you for that, I did notice when taking off the starter that one of the small pegs on the solenoid wasn’t being used at all, my big bolt peg had like 4 wires running off it and the other small peg had one wire running off it. It looked odd to me but it had been running fine until now so I didn’t go too much into questioning it and I assumed the previous owners did it for some reason.

 

The wires coming off the starter solenoid sound correct. Just above those ring connectors on the large terminal are fusible links. There should be 2 of them. One will provide power to the lights, which work. One provides power to most of the rest of your car. Check these closely. Check for power at every fuse. Both sides of every fuse.

 

Soo maybe found the culprit…checked the coil since I hadn’t seen that yet and found this…

 

That certainly doesn't look good! You just might be on to something.

 

Not only swap out the coil obviously, but you really should change the cap, rotor, spring bushing and the rubber washer under the coil.
The spring bushings come in high resistance or low resistance, about $17.

When you install your new coil, a black GRD wire, or a strap goes to one of the four coil bolts in one corner of the coil. Make sure that the GRD connection is touching bare metal of the coil. Some of those coils come with a coating to prevent rust. Lightly file / clean one corner.

 

Yes very closely like bring a nice bright flashlight & look very closely

 

alright so after changing coil, cap, basically everything out I’m still getting crank and no start so I’m chasing after another issue somewhere else causing it.

 

Ignition module maybe ?

 

newest update I went ahead and took it all back apart and checked the ignition module everything looked good basically brand new. It is now cranking but I can hear a loss in power after cranking for just a couple seconds and everything starts to slow down more.

 

Who made your distributor? Was it $60- from eBay?

It may look new, but the ignition module can fail internally. You can buy Delco replacements on eBay. It's always good to have a spare in the car, and add heat sink compound to the back.

Did you check for 12V at the distributor?

Does your battery lack ampacity, and is discharging quickly while cranking?

 

it looks to be legit at least I think it is, the ignition module had Delco on it and it had compound on the back and pretty good amount too. Ya the battery is losing power while cranking, when I put the key in my voltage gauge jumps to around 10 then when I crank it drops to 0 until eventually it loses so much power that the next time I crank it won’t even crank then I have to let it sit for a moment before it’ll actually crank again. When I ran my load test with my meter on both batteries I’ve tried both times I would see a significant drop in voltage when I cranked. Even sitting in the car for a moment with the key in the voltage gauge slowly drops from 10 to 8 and that’s without cranking.

 

Did you check the battery ground at the frame (right under the battery)? Also, check the general condition of the battery cables. make sure they aren't melted anywhere. Do the engine grounds look solid?
As for not starting, do you have fuel and did you verify that you are getting spark? Did you pull a spark plug and crank it?

I agree with Bikespace. I always keep a spare ignition module in an HEI car. They will die without warning.

 

the cables look to be good and there’s no bad spots. The grounds also look to be good I mean aside from needing a little be of cleaning around them they look to be mating with the frame just fine. I did test 2 spark plugs with a tester while I had my wife watch for finally and I’m getting zero spark out of those plugs I tested I went ahead and also pulled a plug and found a lot of carbon build up on the end of that plug and tested spark again with the plug out and had zero spark on crank. Like I had said earlier I know the battery cable going to the distributor isn’t looking great but it’s making a connection I’m pretty sure, I already order a new wire and I’m gonna be changing that out when I get it in.