Maybe it's the way I set it up. I had an inverted ST .60 in a Sig Kommander. The carb fuel inlet was below the CL of the tank. I mounted the pump opposite to the usual way; the plate was mounted on what would be to the top screws on the engine backplate if the engine was upright, but upside down in relation to the head. This put the pump inlet near the tank CL, and the outlet line only dropped ~1/2" to the carb inlet nipple. There wasn't much of a pressure head that way and the pump didn't dribble. I also always took care to keep the throttle all the way closed between flights in order to reduce any tendency to siphon. I also used muffler pressure and a third line for filling. I was told that the pump wouldn't work, being so near the crank but I guess those Sig aluminum mounts were flexible enough to let the pump work. Before I put the pump in, the engine would load up in the midrange. The pump cured that tendency. I flew it that way for several years, no problems. That was a nice model. It had the first sheeted foam wing I ever built.

I wouldn't do all that again. I'd mount the engine sideways to get the carb on the tank CL and forget all that hassle.