Hard to start when warm

[Shazam]

Hi folks. My AMC 304 fires right up when it first starts after sitting a while (I press the pedal to the floor to engage the electric choke) and it also starts fine when started after only being off for a couple minutes (with no goosing of the pedal). But...

It struggles to start after its been run for a little while and sits for longer than 3 minutes or so. It just hesitates for 5 seconds or so trying to turn over. How can I correct so it fires right up all the time?

Thinking it may be vapor lock (it gets hot with the headers)...the fuel filter is behind the carb with the overflow tube on top, but it doesn't sit higher than the carb. I've also covered the fuel lines from the pump to the filter & filter to the carb with DEI heatshield loom.

Any help is appreciated. Many thanks as always.

 

[CJim7]

sounds like vapor lock....I had a hell of a time with my fuel lines when I was running gas, the 401 heats up the engine compartment like a blast furnace. I louvered my hood and that helped, but still....
Do you get a gassy smell when it does this?

 

[Old Dog]

I've also seen enough of the fuel evaporate from engine heat to cause the engine have to turn over a few times so the fuel pump could refill the carb.
Try hitting the gas pedel so you give it a shot of fuel from the excellerator pump.
Remember it is a carb. and not EFI.

 

[jamie]

does it turn over slow? sounds like starter heat soak. but ive never had vapor lock, so im not sure

 

[Shazam]

Thanks guys. I'm going to run some more heatwrap on the fuel lines from the pump back to about the sidepipes or so. They are closer to the headers than I thought. Maybe this will fix it.

 

[Shazam]

does it turn over slow? sounds like starter heat soak. but ive never had vapor lock, so im not sure

it doesn't sound slow...just like there's no fuel to burn. Thanks.

 

[79 Renegade 304]

I see a number of these threads about warm start issues with the AMC 304 and wanted to share my latest experience. I too was having warm start issues and called Edelbrock directly. They recommended a 1" wooden spacer between the carb and manifold due to the issue of fuel boiling out of the bowls when hot, thus creating an issue when trying to start warm.

Bought the spacer at Summit Racing and put it on in about 10 minutes. They informed me that there would be a bit more oomph in the torque following install.

Problem solved with a little kick to boot - the part was $29.95 and made all the difference. So if any ofnyounguys are having this common issue with your AMC 304 4bbl, I would HIGHLY suggest trying this inexpensive solution before running off on a wild goose chase.

My $.02

 

[csuengr]

Slow cranking when warm is also an electrical ground issue. Double check the ground cable bolted to the engine. If it doesn't already have it, put an external toothed lock washer on it.

Carbs will also heat soak. My 2150 would do it, and I had an electric fuel pump. It would take a little longer to start, but no hesitation.