Stalling and flooding issue - 1950 Plymouth

[Mjh]

I have a 1950 Plymouth that starts great cold and after a normal shut down. However if I stall it on a hot day it floods and has to sit about 15 minutes before it will start again, usually with a shot of ether in the carb.  Why is this happening and how can I cure it?

 

[TerryB]

Could be a weak spark that won’t fire on gasoline but will start with starting fluid.  How does it run when it restarts?  Are you sure its flooded and not vapor locked?

[Mjh]

No I'm not sure. How do you cute vapor lock?

[TerryB]

Vapor lock is when the engine heat makes the fuel boil.  The routing of the fuel line from the fuel pump to the carb can contribute to the problem.  Some MoPars, not sure of yours, had a heat shielding piece near the fuel pump to reduce this problem.  A picture if your fuel line routing from pump to carb would help.

 

When it restarts, how well does it run?

[Frank DuVal]

Quick check for vapor lock with most American carburetors of this time period:

 

After it stalls or won't start after a 5 minute sit, with key off, open hood, remove air cleaner, look into throat of carburetor (choke should be open since it was just running and warm), pull throttle to full open and see if a stream of gasoline squirts into the throat. 

 

If there is a good squirt, then probably not vapor lock (yes there are a few carburetors that have some reserve gasoline for the accelerator pump even if the float bowl is empty).

[plymouthcranbrook]

Many add an electric 6 volt pump near the tank to use when this occurs. It will push fuel into the carb.  You can also install a spacer to isolate the carb from the manifold to help reduce heat.  You can  make a shield for the fuel pump and install it over the pump as was suggested. My 52 doesn't have one but I have never had a problem with vapor lock.  Stop by here for more information:

 

https://p15-d24.com/

Edited August 5, 2021 by plymouthcranbrook (see edit history)

[Rusty_OToole]

Could be a weak needle valve, soggy float or misadjusted float. Your car is supposed to have a tin heat shield between the fuel pump and exhaust manifold, a flat piece of metal bent into a J shape. Also, the fuel line should be routed forward, away from the exhaust manifold, then back across the top of the engine. If it gets too hot it can cause vapor lock.

Today's fuel is formulated for fuel injection cars where it is always under pressure and is much more prone to vapor lock than the heavier, oilier fuels made when your car was new.

[ply33]

Rusty has it. . .

 

A fairly common heat related problem on our older Plymouths when parked hot is that the fuel in the carburetor bowl gets warm and expands then floods into the manifold. Not a vapor lock situation (vapor lock would keep fuel from getting to the carb) but heat related flooding. Generally setting the carb float to a little lower than the original specification to account for modern gas greatly reduces or eliminates the problem.

[Hudsy Wudsy]

Here is a helpful article on hard restarting issues and a picture of a Plymouth engine with a heat shield:

Flathead 6 Hot Restart Improvement - Colonial Region Plymouth Owners Club (plymouthcarclub.com)

 

[Bloo]

I'll pile on here as the third to suggest making sure that heat shield over the fuel pump is present.

[JACK M]

I agree on the heat shields, but.

How long will that heater hose last being that close to the manifold?

 

[plymouthcranbrook]

5 hours ago, JACK M said:

I agree on the heat shields, but.

How long will that heater hose last being that close to the manifold?

 

I agree. I have never seen one routed like that.