'73 vette has been cutting off the whole summer, only on hot days (upper 80s and 90s). I have a high performance aluminum radiatior with built in fans so water temp doesnt get above 180 degrees. car starts up great and will run all day without stalling if its a cool day. on a hot day, it will start up normal and run fine for 10 to 15 min. the stalling usually begins at a stopllight, once I have been sitting there for a minute or so. car just cuts right off with out any sputtering or noise, as if someone killed the switch. it will start back up immediately, but as soon and i throw it back in drive (load), it will cut off again. if i hold the brake down and give it a little gas, it wont cut off and i can drive on down the road with no problem. it only happens when stopped, ideling in drive or reverse (auto trans), or even sometimes in park if it is real hot outside. i have made sure that the idle speed is good, so its not that. i also have replaced the carb, fuel pump and distributor recently, hoping it would fix the problem. I believe it is an electrical problem (maybe somewhere around the distributor or ignition switch) due to the car just cutting off so quick and then starting right back up. however, I am certain that the heat has a lot to do with the stalling. can someone please let me know if they have ever seen this problem before?

 

Do you have a fuel pump with a return line to the tank? It sounds like fuel boiling in the carb and flooding the engine. The engine doesn't need to be over heated for the carb to be to hot.

 

I recently installed a holley electric fuel pump with a regulator. Car was doing the same thing with the old mechanical fuel pump with the return line.

 

Your problem is that the fuel is vaporizing in the fuel line or in the carb because of engine heat. If it occurs in the carb, it's likely to be the result of improper insulating plate(s) between the intake manifold and the carb. Most Q-jets require a thick fiber spacer and some take that and a metal heat dissipation plate. Check your A.I.M. to determine what configuration you should have. You can try to reduce the problem by installing some heat insulation material around the fuel line between the pump and the carb; but that won't lessen the need for the carb insulator.

P.S. You also want to make sure that your heat riser valve is working properly. If it sticks closed it will overheat the choke heater passage under the carb.

 

All above comments...

 

Same as other post 1973vette454......"(car stalls when hot,etc)"

Vapor lock is the most probable cause.

Good Luck

 

Hello,

Check your ignition system, loose wires to coil, loose igntion wire from coil. Has your ignition system been upgraded and the points removed? If so this probably is your source of failure, I have seen pickup coils exhibit this exact type of problem. They get heated up and have a bad connection internally.
When the car quits running you should immediately check for spark, if your spark has gone away you are on the right track.

Good Luck,
Douglas in Green Bay

 

Did you ever get this problem resolved?