I have an older 4bL carb on a 460 motor. It doesn't want to start after setting for a few days. If I give it a shot of juice it fires right up but if I don't do that it will just crank and crank. I have been told that maybe the carb is leaking all the fuel out over time while setting idle. What could be the main cause of this happening? It runs fine after it does start.

 

yes it could be draining itself overnight! is the choke closing in the morning like it should ? when first starting it takes more gas and less fuel and once it starts it takes more air and less fuel, that,s where the choke comes in, so it don,t get too much air when you first start it ! did you try pumping it while cranking on it ? when a carburetor drains itself it drains down in the oil, smell the oil to see if it smells like gas !

 

After it has some time to cold soak, remove the air cleaner and look into the carb. Pump the throttle.. do you see the accelerator pump squirt gas? OEM carb, or aftermarket?

 

Now that you mention it, the choke does seem to be about half open even after I set it with the gas pedal. The guy that looked at it works for a forklift company and works on this sort of stuff all the time. He says that when he pumped it by hand he couldn't hear any gas spraying in. He is the one that said it might be leaking out. He suggested a new accelerator pump but like I said it runs fine after I give it a little boost of carb cleaner. I don't use starting fluid, too explosive for me. Yes it is the original carb. There is no gas in the oil.

 

you don,t suppose it,s the fuel pump do you ? maybe the fuel pump is bleeding off ! it,s bolted to the side of the engine in case you don,t know ! did you change the fuel filter ?

 

There should be plenty of fuel left in the float bowl to start and run the engine. Sounds like a possible cracked bowl allowing fuel to seep away slowly while the engine is off.

imp

 

If it is a 4bbl it should have 2 metering bodies. One should contain the accelerator pump diaphram on the bottom which should be held there with 4 screws.
Can you verify if this is what you have ?

 

if it had a cracked bowl then the gas would have no choice but leak into the oil ! this is just a guess but maybe, just maybe the needle valve is not seating good and allowing the gas to drain back into the line and in the pump !