Low Fuel Pressure

[Esser]

I don’t think it will make it harder to start. As soon as you open your fuel valve, the bowls will fill. I like emptying the bowls so if you do get fuel vapour it won’t flood as the bowls can take fuel if there is an expansion

[kmach]

If you have all your engine compartment fuel lines in fire sleeve (recommended), your chance of vapor lock decreases, allot.

In summer, I usually open the oil cap access door after shutdown, it lets allot of heat out.

I did install the fuel return line when installing the new engine ( as per Rotax's instructions), but I never ever had vapor lock with the old engine with no fuel return line.

[jiott]

I also believe firesleeve helps a lot, and have started opening the oil access door after shutdown. However, I do this mainly to avoid cooking the expensive ignition modules.

Vapor lock is a funny thing; I have the fuel return line and never had a vapor lock incident for about 3 years. Then one hot summer day (about 95F) I shut down for maybe 10 minutes on a gravel bar. I restarted OK and immediately started my T/O roll. Suddenly the engine lost most power and started coughing but didn't die. I aborted the T/O and shortly the engine was running fine again. I am sure it was vapor lock due to the short, hot shutdown (had not opened the oil door), but the fuel return line soon circulated cool fuel to kill the vapor lock. Lesson learned: after a short hot shutdown I need to let the engine idle for a while after restart before attempting an immediate T/O. This has never happened again, but that one time it could have had a very bad outcome.