Well, here it is, i'm running a saito fa-65 on a decathlon 40.
On the ground the plane runs awesome..Now when u pitch up it still runs awesome. but once you pitch down right after the pitch up attitude, the engine quits...It happened to me today during takeoff and i lost the engine about 20 feet from the ground.....I managed to settle it down with minor injuries.
Is there a problem with my plumbing?
On another note, with my current plumbing, i prime the engine before start by blowing into the tube that goes into the silencer....For some reason, plugging the silencer and rotating the prop backwards doesn't prime enough....
HELP!!!!!
Thanks,

Dave

ok make sure the clunk is where it is supposed to be and hasn't shifted around and stuck somewhere high in the tank. do you see any fuel leaks you may be losing head pressure from the muffler as the attitude goes nose down. lastly replace the fuel line to the clunk its covered by fuel nose high so no leak but as the attitude goes nose down it may expose a pin hole causing a leak back into the tank and fuel starve your engine. as far as the prime goes try this open the throttle all the way put your thumb over the carb and rotate the prop in the direction of rotation until you see fuel just touch the carb and start normally. be sure to close the throttle again before you start.
let us know what you find

Hi!
The plumbing looks good...but I prefere a third line going parallel to the fule intake line in the tank (Called Uni flow set up).

It sounds as if you run ithe engine too lean! Open up the highspeed needle somewhat and try again. The engine should never rew max when you hold it straight up!

You say you can't prime the engine without blowing in the pressure line (pressurizing the tank)This sounds like you have set the low speed needle/idle needle too lean ...screw it out just a quarter of a turn and see what happens.

Regards!
Jan K
Sweden

clunk tube came off inside the tank.....I'll try now and let ya'll know...
I'm re-tuning the needles (high and low) and i'll see what happens....Wish me luck and i'll post tomorrow to tell u the outcome..