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Old 11-11-2012, 10:48 AM   #7
63burban4x4
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Join Date: Mar 2012
Location: US
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Re: carburetor lags when I punck it

Quote:
Originally Posted by oem4me View Post
Look down into the carb with a flashlight and hit the accelerator. You should see a healthy stream of fuel squirt into the throat. If you do not see that upon working the accelerator, then your accelerator pump is bad, or more than likely it's outlet is plugged. Clear the hole with a wire and away you go.
If however you do see a squirt, then look into your timing.
X2. IIRC, the fuel normally is drawn into the carb barrel by the venturi effect. Air rushing down the barrel past the venturi, draws fuel into the airflow. When you stomp the pedal, the throttle plates instantly allow more air, but it takes a second or two for the venturi effect to provide more fuel. The accelerator pump overcomes that momentary lack of fuel with a little extra fuel "pumped" in, That little squirt of fuel provides enough fuel until the venturi effect takes over. Easy then to understand the "stumble" , if the accelerator pump isn't working. It's been a while, but I think the accelerator pump has a rubber diaphram, which is pushed down by the accelerator pump linkage, pushing a little fuel in front of it. That rubber plunger can dry out, crack, and fail. At least that's how I remember it...LOL. The real mechanics here can correct me if I'm wrong.
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