Jump to content

1947 plymouth won't start when warm, advice?

Recommended Posts

1947 plymouth starts and runs great but won't restart when warm.


I insulated the fuel line and adjacent exhaust manifold to prevent vapor lock but no improvement.

any advise?

Link to post
Share on other sites
1 hour ago, rad4848 said:

Thanks for the info but I don't know where to purchase this in my area( Chicago metro area).


It is sold for boating, maybe around a marina.

Link to post
Share on other sites
Posted (edited)

Heat sink maybe?....The hot engine. Heat travels up the engine as it sits after being shut off. The coolant temp gauge in the cab will rise, you'll notice when you shut off a hot car. This is normal. This heat can boil the fuel in the carb bowl and cause it to evaporate. A phenolic spacer between the carb and the intake manifold may help prevent heat from rising up into the carb. Also ensure your thermostatic exhaust valve (bi-metallic spring) is closing once the engine heats up. So it stops directing hot exhaust gasses up toward the carb base.


I find in this heat soak situation, flooring the gas pedal while cranking, allows the engine to start. A back up electric fuel pump that you can switch on for a few minutes helps too. It tops up the carb bowl before you are cranking the engine using the mechanical pump.


Failing coils that get hot, also don't want to work. Have you confirmed the coil is ok when hot? You have spark present?





Screen Shot 2020-06-08 at 12.11.45 PM.png

Edited by keithb7 (see edit history)
Link to post
Share on other sites
1 hour ago, Bloo said:

Aren't these engines supposed to have a shield over the fuel pump? Is it there?

Yes they had a heat shield but it was needed at a time gas was gasoline and before ethanol. Now things are worse.

Link to post
Share on other sites

Thanks all for the advise.


I will look for a marina that sells non-ethanol fuel, check for spark and follow the carburetor shop's suggestions for hard starting, hot.


Hopefully one of these will reveal the problem and resolve the problem.



Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...