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Tristan



You mentioned that you do not have a header tank and that you have a fuel

selector that has positions for R - L - Both and off.  A both position in a

low wing aircraft is considered dangerous by the FAA and not allowed in a

certified low wing aircraft because if one tank unports or runs dry before the

other one the fuel pumps would suck air even though fuel is present at the

other port.  I have been flying a Lancair 290 for some 7 years without a

header tank and  do not have a both position on my selector for this reason.



Another problem I encountered while testing was that I originally had the

electric fuel pump installed after the Gasgolator like the manual shows and I

ran into some funny problems.  First I experienced what appeared to be vapor

lock.  Second the primer would not work right because it would not fill up all

of the way because there was no pressure at the input to the Gasgolator ( No

Header Tank)   After checking around I found that with a low wing and no

header tank the electric pump needed to be installed before the Gasgolator to

pressurize the gasgolator.  I changed mine by installing it in the cabin on

the fire wall.  It now stays cool (no Vapor Lock Problem) and the primer works

fine.  Now that I am building a Lancair IV I found that thats how they do it

too.  Please consider changing your fuel selector to a R-L and off only or at

least Placard to not use both for take off and landing or when the fuel level

is below about 7 or 8 gal in either tank.



Regards Tom Byrnes N133TB