Whats My Problem?

[66 Valiant]

66 Valiant 273 completely stock with a lot of original parts under the hood.
(Just got the Valiant this summer and I love it)
Driving down the road on a hot day and the engine stalls out. Cranks over, fires once or twice and then won’t start after cranking it over many times. I wait for 10 to 15 minute and it fires up runs great. Two weeks later stuck in traffic and it does the same thing. Not sure where I should start. I’m thinking fuel? A friend suggested fuel vapour lock, but I’m not sure what that is.
Any suggestions would be greatly appreciated.

 

[fishy68]

Stalling out like that can be fuel or ignition related. First thing I'd do is drive it until it quits then get out and pull the coil wire and place it about 1/2" from a good ground and test for spark. You'll need someone to crank it over for you while you watch. The spark should be a good solid blue spark. If it has no spark or weak spark it's ignition related and that could mean a bad coil or a bad condenser (assuming your car hasn't been switched to electronic ignition). If it has been changed to electronic ignition the ignition box may be bad or the magnetic pickup in the distributor may be bad. One other thing that causes no spark is a bad ballast resistor but they are usually either good or bad. They don't usually open up when they get hot but anything is possible. Last but not least is a breakdown in the electrical wiring somewhere not supplying power to the ignition circuit.

If it has spark we assume all is good with the ignition system so move on to the fuel system. Pull the air breather (make sure the key is shut off) and look right down the throat of the carb (wear safety glasses if possible) and push the carb linkage by hand and watch for a spray of fuel in the carb barrels. If no fuel it's fuel related. In that case it is either a clogged fuel filter, bad fuel pump, or could be vapor lock which BTW is when the fuel gets so hot in the fuel lines it turns to vapor. Vapor can't be pumped so it's the same effect as running out of gas. Vapor lock is generally caused by a fuel line that is in close proximity to a hot engine part that causes the fuel to vaporize. Look the fuel lines over good and see if any are close to something hot. Some cars also have a fuel "sock" in the gas tank that is essentially another fuel filter and it can get clogged.

Do these tests and report back and we'll go from there.

 

[RustyRatRod]

Try this. It's CHEAP. IF it's vapor lock, this will work. Get several wooden clothes pins and clamp them to the fuel line. All of um that'll fit. If it stops doin it, it was vapor lock. The clothes pins remove some of the heat that builds up on the line and in the fuel and stops the problem. Of course, I've seen people just leave um on permanently, but you need to fix the problem if that's what it turns out to be.

 

[blackbomber]

A longshot, but I have had similar symptoms with a failing choke (stays closed). But my first guess would be a bad coil or condenser, as suggested by fishy.

 

[RedFish]

Coil overheating or fuel filter cloging. If there isn't any oil leaking out of the coil ,change the inline fuel filter. There is another filter some call a sock in the fuel tank.
Then there is a short piece of rubber hose at the tank that may be the culprit.
Anyway... as others have said, first determine if it's fuel or spark that is failing