air in the gas line

[Torino 14]

I cleaned my carb and replaced the lfuel ine from the fuel pump to the carb on my k301. I ran it for at least ten minutes and there was still a lot of air bubbles in the gas line. Is this normal? Gas tank was 1/2 full.

[BairleaFarm 340]

Are you seeing the bubbles in the filter?

[WheelHorse_of_course 99]

Yup, completely normal. I believe it is vapor not air, but in any case it is quite normal not to mention common.

I replaced the fuel line on my Charger 12 and decided to leave some slack for future fuel filter replacement (all too often you can't get the line off the filter and have to cut it). I sort of looped it and there is a section that looks empty most of the time (plus the filter looks mostly empty too). B)

[Torino 14]

David, I have a clear line running from the pump to the carb.

[TT-(Moderator) 1,131]

It's normal to see air in the line between the fuel pump and the carburetor. I'm almost certain that this is caused by the pulses of the fuel pump and the fact that the needle and seat on the float isn't always closed and is surrounded by air, not gas. Once the pulse of gas travels up the line, it will actually drop back down toward the pump until the pump cycles again. When the gas travels backward in the line, it sucks the air from the float bowl with it, causing "bubbles". Sometimes the air makes its way back through the check valve in the fuel pump and into the line from the tank.

You'll rarely see bubbles on a gravity fed fuel system, and I doubt you'd see it with a constant-pressure electric pump either.