Minimal damage after I crashed my kitfox. I got it on video!

For a vapor lock issue would a longer run up prevent any issues with this?

What are ways to 100% avoid/prevent vapor lock?

You can reduce the chance of having vapor lock by;


Have a restricted fuel return line to your header or wingtank.
Having your fuel lines in heat sleeve.
Parking facing into the wind. Opening your oil tank access lid after shut down to let hot air out.
Running your engine for a reasonable amount of time to do your checks before takeoff.

Five words: Backup Flow-thru Boost Pump

Also, MOGAS (which is what I use) is more susceptible to vapor lock than 100LL due to lower boiling point.

At 1,400 hrs. the only 'engine failure' I've had was similar to Jonas': it quit on rotation on a gravel bar on April Fool's Day! Fortunately, the wheels were still on the ground with plenty of overrun left.

After that trip, I took apart the return line and inspected the orifice, check valve, and the entire fuel system. All AOK. I ass-umed vapor lock...

Thanks to all for the ways to inhibit vapor lock!

I also had what I am fairly sure was vapor lock after landing on a gravel bar on a hot summer day. After about a 10 minute shutdown I fired up and on the T/O roll it started to stumble badly. Fortunately, like Floog, there was plenty of room to get stopped. I let the engine run a while and ran it up to hi rpms and it soon smoothed out and ran fine with no more problem. I do have a return line to the header tank (factory kit) and fuel lines in firesleeve.

Lessons learned:
- You can have vapor lock even with a return line, but I believe it is not as severe and clears itself more rapidly.
- Gravel bars are especially bad places.:D
- On a hot day after a short shutdown, ALWAYS run the engine and do a hi rpm runup before T/O.
- I have been trying to train myself to open the oil door after a hot shutdown. Not only is it good to prevent vapor lock, but it also will extend the life of your ignition modules I have heard.

The heat buildup after shutdown is surprisingly high.I run a temp probe near one of my carbs,15-20c on cruise 45- 50c after shutdown.this is on a round cowl,I would guess the smooth cowl temps may be higher.opening the oil hatch sounds like a good idea!

I find this discussion fascinating. Along the way, I am constantly recalling my experiences with the numerous cross country and back country trips we took as a flight of six or so. All Kitfoxes except the two Rans - S6 and 7. Thinking about it, it is likely the shortest times on the ground were fuel stops but with six or more airplanes it likely took close to an hour or so total. Then all were TD's except the S7 with ample air flow up through the bottom cowl exit through the sizable air outlet at the high end - at least while on the ground. Vapor lock was never ever an issue. I am extremely curious what it is that has triggered the problem. The Avgas vs. Mogas might be part of it but back then we often found mogas at some airports.

The picture is at Rome Station, Oregon - a restaurant and gas station on Highway 95 with a dirt strip out back - I guess we cheated.

Hello Guys,
Been following this group for the longest time and have used tons of knowledge from here. I though I will share my 2 cents of experience and knowledge on this subject. I had 6 "vapour lock' indents with 912 in a Zenith 601....right after I followed the mendatory AD from Rotax to replace old 'Piersburg' pump with new style pump (BCD/corona). I was lucky on incidents every time, either there was enough landing option available or enough altitude available to pull throttle back to about 30% and get the fuel flowing again. Yes, I have extra Facet pump to help but major issue is that when this happens on new style pumps, it even restricts the pressurised flow from auxiliary pump to flow thru.

Having said this and long story short, experience dealing with Rotax on the incidents was not pleasant and in spite of following everything they advised including installing the return line to main tank. It kept happening on moderate warm days....till I switched back to my original fuel pump and already have over 100 hours on the setup after that without missing a beat.

Food for thought is that everything is kept the same in terms of air flows, exhaust setup, fuel lines and insulation on them type of fuel (MOGAS) and even to a point that return line was also temporarily blocked with no issues. The new style 'Corona' (BCD) pumps seems to have a bad design and enough void volume to create this problem. I have also ended up switching a new style fuel pump on one of my friends 'Skyboy' with duel facet pumps in a redundant setup with pressure sensor after he had long frustrating episodes of rough running and vapour lock issues. Yes, now he is dependent on voltage for flying but its better than having unforeseen sudden engine out or nasty vibrations.

I curious about what you had to do to get the airplane home.

His next video is gong to be all a out that.