How to Troubleshoot Walbro Carburetors

by Alibaster Smith

Walbro carburetors are, by design, very reliable. Although carburetors are no longer used on production vehicles, older vehicles that are still on the road do use them. A Walbro carburetor draws in air from outside the engine bay and mixes it with gasoline. The fuel is then sent to the engine to be burned. If you are experiencing a rough idle, you should do some troubleshooting to discover the source of the problem. Fortunately, there are only two common problems with the Walbro carburetor.

Start the engine and check the idle speed. The carburetor should be mixing the air and gasoline at a 14.7-to-1 ratio. If it is not, the idle will drop below 500 rpm on the tachometer.

Open the hood and locate the two screws at the base of the carburetor. These screws are the adjustment screws for the Walbro carburetor. Turn these screws counterclockwise with a screwdriver to allow more air into the system and, consequently, produce a higher idle speed. If the idle does not increase when you turn the screws, then the problem is likely the Walbro's filter screen.

Locate the screw on the side of the carburetor. This screw holds a screw plate in place. Remove the screw, and you'll be able to see a screen. Walbro uses an internal filter screen; unfortunately, it becomes dirty rather easily. If you see any debris on the screen, remove it and clean it (or replace the screen).


  • check For specific information about your vehicle's model of Walbro carburetor, consult the particular vehicle's manual (see Resource).

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About the Author

I am a Registered Financial Consultant with 6 years experience in the financial services industry. I am trained in the financial planning process, with an emphasis in life insurance and annuity contracts. I have written for Demand Studios since 2009.