Gas Dripping From Venturi

2 Jet Venturi

Gas dripping from the venturi can happen on most carburetors, but we will talk about the Mercarb and the Rochester 2 Jet, 2 barrel.

The only time gas should come out of the venturi is when you pump the gas throttle. That is when an extra squirt of gas is required from the accelerator pump circuit. Make sure the engine is off when looking down the carburetor bore.

If it happens at idle, or cruising along, then you have a problem. This can be caused by a vacuum leak, or something plugged in the idle circuit.

Remove the idle mixture screws and blow out the circuit. Remove the venturi and blow out the small holes on the top. You may have to run thin wire down the holes to get them clear.

Still have the problem?
You could be getting too much gas. Check the fuel pressure to see if it is 4.5 to 5 lbs. Also check the float level. On the Mercarb turn the top upside down and set the float level.

Another thing to try. Start the engine and bring up to temp. Rev up the RPM to 2500 or so and cover the air intake with a gloved hand or rag while leaving the at same 2500 or so position. The engine will begin to die, but just before it dies let it recover. Repeat this several times. What happens is fuel goes through air/vacuum circuits and visa versa. If the idle circuits are dirty this often flushes them out!

One other possibility is “heat soak”. This happens when the engine gets hot and you turn it off, or come to an idle. The fuel boils over, causing it to flow out just about anywhere it can. If this is happening, try other brands of gas. Without ethanol if possible. Ethanol is not our friend.

 

 

 

One Response

  1. Les Merrill

    I really appreciate these articles. Being a car nut with shade tree skills I find this helpful.

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