I have an external, inline fuel pump feeding a TPI V8.

It was somehow sucking big bubbles into the lines, killing the pump/pressure and making the motor run rough. After going in a tightening all the fittings (even in the tank) and that made the pressure better... but you can still see tiny bubbles in the return line. Is this normal?

I don't want to put it all back together if there is still a problem to chase down. Since it's not back together, I don't know how it runs, only that there is still a small amount of air bubbles.

Tnanks in advance

Sounds like a leak in the intake tube in the tank.

JazzMan

yep... thats what we thought to, until we pulled the whole tank assembly apart and dunked the whole pickup assembly in a tank with 100PSI through it and there was no bubbles.

Ended up going piece by piece, dunking everything under pressure --never seeing a bubble anywhere. I was starting to think maybe the pump had a cracked casing, but it's new and looks fine.

Can't figure it out!

You could have a leak on the tank side of the pump that allows air in (because it's a vacuum) but not air out, so a pressure test may not reveal a leak. Put a vacuum pump on the line and see what you get.

JazzMan