Originally Posted by
Hobbsy
Sam, as near as I can find your 1.20 does not have a special carb. If I may ask what glow plugs are you running, normally you only need to light one and the combustion lights the other one instantly. You're not the first to be frustrated by the pump arrangement. You'll be chasing your tail as long as you fool with it.
It puzzles me that so many have issues W/the pump.
Just set it and forget it. If you fiddle W/the pump, the needles on the carburetor will need to be adjusted. My FA-300TTDP runs great W/the pump as does my high compression FA-180 W/the BB FA-220 carburetor.
What you have the remember is that the pump needle is the opposite of the carburetor needles. Screwing the pump needle in increases pressure, thereby making the A/F ratio richer. I experiment by turning up the pump pressure, then checking the carburetor needles. Generally, screwing the pump needle in will require a slight leaning out of the carburetor needles. (screw the pump needle in/screw the carburetor needles in) I try to run as much pressure as I can and still get reliable idle & transition. It's my take that higher pump pressure atomizes the fuel better & gives a more efficient burn.
You can just leave the pump @ the factory starting adjustment if you like the results..
The great thing about the pump is that fuel delivery will remain constant regardless of the fuel level in the tank in relationship to the spray bar. It will also allow the tank to be mounted farther back over the CG.
The duel carburetors on this FA-300TTDP are very high above the tank centerline yet it idles, transitions & runs @ WOT very consistently regardless of the fuel level.
https://www.youtube.com/watch?v=vdmLu13UJzs