Today I tested the fuel purge valve. I installed the purge valve to provide easy starting under hot engine conditions. A hot engine at rest can cause fuel in the lines to vaporize and cause difficulty during start attempts. The purge valve allows you to pump cool fuel from the tank into these fuel lines and make a hot start the same as with a cool engine.
I wanted to get a feel for the fuel flow during this process so I disconnected the return line from the purge valve and connected some spare tubing and ran it into a plastic container to catch fuel.
With the boost pump on and the purge valve in the "run" position (knob pushed in on the instrument panel), the fuel system is in a normal operating condition. Fuel flow is controlled by the throttle and mixture knobs. In the test today when the throttle was open and mixture rich, some fuel flowed into the cylinder combustion chambers and into the sump and out the sniffle valve. (This is expected as this was a"flooded" condition).
With the purge valve in the "return" position (knob pulled out) the fuel is routed from the valve back to the right tank supply line. Again the flow of fuel is controlled by the throttle and mixture knobs. In the test today when the throttle was open and mixture rich, fuel flowed through the return line and into the plastic container as expected. This flow is fairly low, as expected.
I was satisfied that the purge valve was operating as expected and reconnected the fuel lines.
