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How Does a Fuel Valve Work?
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Technical Advice
Many honda mopeds and scooters use a vacuum operated fuel supply valve. It is on the bottom of the tank, and has two hoses going to the carb. The larger one is the gas line, the smaller is the vacuum line.

When the engine is running, the vacuum line turns on the fuel valve, allowing fuel to flow into the carburetor. When you run out of gas, so there is none in the carb at all so the engine will not run, and you add fuel to the fuel tank, you need to crank the engine over about 15 seconds to allow the fuel valve to open long enough to fill the carb and start the engine.

Many other brands use similar valves on their mopeds, and many are located on the frame, separate from the fuel tank. Razz, Sundiro, most Chinese bikes, Suzuki FA 50, and many others use this type of valve.

To test the valve, unhook the smaller (vacuum) line from the engine intake manifold and suck on it. (apply vacuum). This operates the diaphragm in the valve, and fuel should flow out. If fuel always flows, even when the vacuum is not applied, the valve may be stuck, or dirty.

Scooter Therapy Inc
12 North Few Street  |  Madison, WI 53703    
toll free 1-800-411-1543  |  local 1-608-255-1520    

fax 1-608-255-1587  |  E-mail

Scooter Therapy Inc    

12 N. Few St     
Madison, WI 53703 

toll free 1-800-411-1543    
local 1-608-255-1520    
fax 1-608-255-1587    

Hours: M-F, 9-6 Saturday, 10-3  CST

copyright (c) 2000
Scooter Therapy inc.