Vapor Lock?
in 912 / 914 Technical Questions
8 years ago
Flew the RV-12 and a couple of items caught my attention today. Weather in northern Ohio was 68F thanks to the massive El Nino.
I flew an uneventful 30 minute flight, landed, and shut off engine. Airplane sat for about ten minutes. I restarted the engine and within about 30 seconds it began to shake and then quit. Restart went well and all indicators were in green. I did a complete run-up and engine performed well. Takeoff for my second flight was fine. About five minutes into the flight I got a high fuel flow warning with fuel flow around 12 GPM. High readings remained for a couple of minutes. I slowly reduced power to about 50% and GPM went back to 4.5ish. I gradually returned to cruise power and fuel flow remained fine for the duration of the flight.
I think the fuel system got a vapor lock when sitting with a hot engine. Under-cowl temperatures most likely vaporized fuel in the lines and perhaps even the carb float bowls. I buy this explanation and will remember symptoms for future consideration.
My question is why the elevated fuel flow readings? Is this vapor lock bubbles returning to the fuel tank? Any ideas appreciated
I flew an uneventful 30 minute flight, landed, and shut off engine. Airplane sat for about ten minutes. I restarted the engine and within about 30 seconds it began to shake and then quit. Restart went well and all indicators were in green. I did a complete run-up and engine performed well. Takeoff for my second flight was fine. About five minutes into the flight I got a high fuel flow warning with fuel flow around 12 GPM. High readings remained for a couple of minutes. I slowly reduced power to about 50% and GPM went back to 4.5ish. I gradually returned to cruise power and fuel flow remained fine for the duration of the flight.
I think the fuel system got a vapor lock when sitting with a hot engine. Under-cowl temperatures most likely vaporized fuel in the lines and perhaps even the carb float bowls. I buy this explanation and will remember symptoms for future consideration.
My question is why the elevated fuel flow readings? Is this vapor lock bubbles returning to the fuel tank? Any ideas appreciated
