Hi everyone,

I need some thoughts on the following problem. Is this a fuel or spark issue? (Or operator error)

1973 Vette
Stock quadrajet, rebuilt and cleaned
Small block 1997 motor with comp cam, Vortec heads which runs like a top (when it starts).

Drove to meet a friend for breakfast before a Houston car show. Probably a 45 minute drive to the restaurant. Car ran fine. 1.25 hours later after breakfast and shooting the bull, we hop in my car to go to the show. It will crank and crank but not even pop or sputter. Seemed like there was no spark. Doesn't sound or smell flooded. Tried 8-10 more times but nothing. Popped the hood looking for anything obvious.

Disgusted, we hop in his car and go to the show.

3-4 hours later, we return with a can of starting fluid and a bad attitude but never had to use the fluid. Car cranked and within 2 seconds was purring like a kitten.

I'vegot a Carter electric fuel pump right by the tank. Bypass/return goes right back into tank . Main fuel line from pump goes to carb. No return line from carb.I assume the fuel is vaporizing in the line near the motor after it sits when hot. Once it cools, fuel can flow again.

Whatdo you think? Vapor lock? Issue with a hot HEI ignition? Something else?

Thanks for any help or suggestions.

Larry in Houston

 

not vapor lock an hour and a half later. should be cooled off enough for pump to pass liquid
install a fuel line pressure gauge.
can you hear the pump during the problem?

 

Yes, you can hear pump "on" the entire time.

 

OP
WAG ... heat-soaked and/or faulty HEI Module ?...they're cheap & easy to swap out.

 

ensure there is heat transfer paste between bottom of ign module and distributor's module mount pad.

https://www.bestbuy.com/site/insigni...E&gclsrc=aw.ds

https://www.ebay.com/itm/High-Perfor...YAAOSwZ2FcUfyA

 

One sign that your coil is getting ready to fail is that the car will not start when the coil gets heat soaked.
Another sign it’s going bad is the engine will quit running while you are driving down the road with no warning.
A few hours later after you get towed home it will start fine and run without a miss until the coil warms up and fails again.
Coils are cheap, swap out the old one and see what happens.
Even a new coil can fail without warning.
Let us know what you find.

 

^ +1 Same thing kept happening with my camaro. Changed the coil and haven't had any issues.

 

1970 corvette, I had the exact same problem, switched to ethanol free gas and the problem disappeared. My hot start problem was 30 to 60 minutes after a hot engine was shutdown. Starting before or after that time frame and I had no issues.

I'm also running an electric fuel pump. When hot I could get the car to start but it took really a lot of cranking, enough cranking I was afraid the battery would go dead. I believe the fuel was vapor locking in the fuel line where it ran across the top of the motor. I also insulated my fuel line and have never had an issue since.

Hope that helps.

 

Looks like the culprit is the HEI coil. I'll test asap and report back.

 

Lots of test drives and starts over the past two weekends after changing out the HEI coil. The car starts perfectly every time. It could be just me but I swear that it idles and runs better as well.

Thanks again everyone for the suggestions and help.

Larry