I had two airplanes whose engines would quit in the air after a few minutes. Both had an annoying problem with bubbles in the line for different reasons.

First, for my KAOS, I wanted to seal off the engine compartment from tank compartment. I made sure the hole in the firewall, through which I ran the fuel line, was a snug fit. Bad decision. Vibrations, transmitted to the line, were causing bubbles. After opening up a larger hole to allow the fuel line to pass through the firewall without makng contact, the problem was solved.

Second, for my Sr. Falcon, I stuffed a rather large tank, surrounded with latex foam rubber, into the compartment. Pressure was required to hold down the hatch so I could secure it to the body. As a result, I was squeezing the foam down to the point where it no longer damped the vibration. After making a new (bulging) hatch to allow the foam freedom to expand, the problem was solved.