Vapor Lock

[Agfoxflyer]

I have a 912 ULS (series 5 smooth cowl) that will not re-start after a flight. It has to cool down for a long while before it will re-start. I had been shutting fuel supply off when taxing up and letting the engine run until all the remaining fuel in the lines was used up. It would restart immediately this way. Until recently I was using mo-gas but can't find it any more without ethanol, so I've switched to 100LL. I had heard that mo-gas was more prone to vapor lock, but don't know if this is true. My last flight it wouldn't restart until cooling down even when running all the fuel out of the lines. I have heard the newer installations have a return line. Is there a kit or instructions and is it easliy done on a finished airplane? Anybody know?

[DanB]

Not sure if this could be part of the problem but are you using a lead scavenger mixed with that 100LL?

[Agfoxflyer]

Dan, Yes I am using Decalin.

David

[Av8r3400]

Per both Lockwood and LEAF, the return line should help vapor lock issues. I think they both have inexpensive "kits" for the installation.

In a nutshell it is a "T" fitting, with a restrictive orifice, between the carbs and the fuel pump which will allow pressure to return to the (header) tank but not enough flow to cause fuel starvation.

There was much discussion on this at the Airventure forums.

[Nathaniel]

I just installed all the fittings in my header tank (almost ready for install) and I'm out of holes. How do I go about the return line setup? Nothing in the Kitfox manual and I won't be buying an engine for at least a year.