Carburetor Trouble Shooting: Accelerator and Power Circuits Diagnostics

In this article I will go over how to trouble shoot your accelerator and power circuits inside of your carburetor. My previous articles on carburetors can be found here in my library of automotive articles. The accelerator and power circuits of a carburetor comes into play when you are at cruising speed and you are trying to either pass a car or you just want more power. You will experience a very bad hesitation or you will notice that you have no power at all.

I will first explain the accelerator pump circuit and how to diagnose a bad one. Your accelerator pump circuit consists of your throttle linkage, check ball and spring, rubber diaphragm and small ports of which your gasoline travels through. A really good indication of your accelerator pump not working right is when you are trying to start your car for the first time after your engine has cooled. If your car or truck has to be pumped numerous of times to start then its more than likely that your accelerator pump diaphragm has rolled and is not pumping any more.

Pull the air filter housing and look down inside of the carburetor's throat with a flash light and look for a steady stream of fuel shooting out as you slowly open up the throttle plate. If you see a small spurt only then this circuit will need to be repaired and fixed. You can either remove the top portion of the carburetor and replace the spring diaphragm or you can leave it up to a service professional.

The carburetors power circuit can be diagnosed in this way. Apply some wheel chocks under the wheels and crawl inside the engine compartment with a can of carburetor cleaner. If you have an Exhaust Gas Recirculation Valve installed pull off the vacuum port and plug it with a golf tee. If not then you will get a false test response. Steadily increase the engine's rpm and hold it around 2000 rpms. Now when you feel the engine start to bog down spray a little cleaner inside of the carburetor. If you see and feel the engine rpm increase while spraying then you know your power circuit is either plugged up or dirty and will need to be fixed or replaced.

What you are doing in this trouble shooting test is finding out if the car is starving for fuel while you are trying to accelerate. By spraying the carburetor spay inside of the carburetor you are giving it the needed fuel to give you more power.

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