The Stovebolt Site Forums The Shop Area Engine Shop Flooded Carburetor

I have a 1954 chey 235 engine with a rebuilt Rochester 1b carburetor that runs great but right after a shutdown, gasoline drips inside the carburetor for a while flooding the engine. This makes it very difficult to restart the engine soon after shut down.

If I wait for 30 minutes or so, the gasoline evaporates out of the carburetor and starts right up.

The gas tank is vented so gasoline is not siphoning from the tank and the engine runs great other wise.

Any suggestions?

From the troubleshooting section of my website:

HARD STARTING, HOT


Difficult starting of a hot vehicle from 5 minutes to an hour after the engine has been operated, can be caused by the volatility of modern fuel. If you have this problem; try using the following method to start the engine: DON’T touch the footfeed (VERY important). Crank the engine over from three to 5 seconds (different vehicles will respond to different times); and then GENTLY (so as not to activate the accelerator pump) press the footfeed approximately 1/3 of its travel. The engine should start, and may run rough. Run the engine at a high idle for about 10 seconds. This issue is caused by volatility of modern fuel. Once the engine has been shut off, the gasoline is heated by the latent heat of the engine, and percolates the fuel from the bowl into the throttle area, forming a mixture that is too rich to fire. If you push the footfeed to the floor (as has been the traditional method of “unloading” a flooded engine) the gasoline continues to flow into the engine (again due to the volatility). By not touching the footfeed, you do not open the throttle plates, and the engine will pump the overrich mixture out of the tailpipe. Once the overrich mixture has been alleviated, gently opening the throttle will allow the engine to start.


Jon

Thanks Jon,

The starting method does work. I guess this flooding problem is not going to go away so I'll have to live with it.

Thanks again


Bosco

It would seem to me that the float is a bit higher or the float needle is not closed for some reason

After driving the truck and shutting it off, look down the throat of the carburetor and see if you see dribbling or gasoline pooling on the intake runner. Fuel may be leaking past the accelerator pump or over-topping the bowl.

Yes Otto, gasoline is dribbling inside the carburetor after shutting it off. There is no leaking while it is running and it stops leaking after a few minutes after I shut it down. Besides that, the engine runs great so I'm thinking that the float is adjusted ok and the needle is seating properly.

If fuel is leaking past the accelerator pump ( do you mean gasoline leaking past the accelerator pump leather cup plunger?), would the engine run perfectly fine?

Tex makes a good point about your float level and needle valve. This seems more likely if your engine is running smoothly and accelerating smoothly.

Your float level might be too high, especially if the fuel expands when hot and overflows. The valve may not be seating properly or some crud might be blocking it.

Check your fuel pump fuel pressure at the carburetor. It should be between 2psi and 4psi. More than that can cause fuel to push past the needle valve and overfill the bowl.

Squirt a puff or two of air into the carb inlet to dislodge any debris that might be preventing correct operation of the needle valve. I'd also lower the float level slightly to see if that fixes the issue.

Usually a leaking accelerator pump also causes stumbling or bogging as well as hard starting. Test the accelerator pump also by looking down the throat and goosing the throttle manually. You should see a healthy squirt of fuel.

You were right. I readjusted the float from 1 9/32 " to 1 5/16 " and that fixed it. Thanks Tex and Otto.

That's great. Easy fixes are the best kind.

Hi Bosco,
Same problem. After trying all the above, found a pin hole leak in my carb.
Chuck 52

Chuck52, Do you mean there was a pin hole leak in the carburetor float?

Yes, Otto.
Pin hole in my float. Thank for noting and following up on my mistake, Otto.
Was able to purchase an original type brass float from Yesteryear Antique Auto Parts located in Florida. Excellent quality. Solved flooding problem.
Chuck