Jabiru 2200

[Ken Raven]

Jabiru 2.2
I fly a Jab powered ultralight down here in Spain and with the usual hot summer ( we usually fly early in the day) I’m having a few problems with vapour lock! Only Mogas readily available, correct me if I’m wrong but locating the fuel pump behind the cylinders instead of up front in the intake does seem strange!

[Clive]

It’s a difficult one. I have always been surprised with the amount of temperature problems the Jab has, especially the early ones and they were developed in Australia....
Given a cold blast tube for the pump will only spoil the head cooling my only thought was for a spillback line tee’d from the carby inlet back to the tank. Needs sizing carefully as I don’t know the pump flow. The electric is good for in excess of 60 and the engine uses less than 40 full chat I believe. Or run an electric one all the while. The circulating Fuel will cool the feed to the tank temperature. Maybe put a valve in the spill back so you can turn it off for critical phases or when established flying and the normal flow of fuel at tank temperature won’t be flashing vapour off.
For those that know mogas, are the higher octanes like ‘Super’ unleaded’s less likely to flash vapour off?
Good luck, regards Clive

[mikehallam]

Best ask this question on the Jab/Camit forum where many active engineers & experienced user worldwide exchange gen. (If not done already ?)