Air bubbles in fuel supply?

[arter]

Put a clear glass fuel filter between tank and low pressure pump for EFI. Have alot of air bubbles coming into filter from tank side. Took hose off tank and stuck in gas can, smaller bubbles, almost foamy, but seemed like more fuel too. Like to know if this is normal, have had an ongoing problem with cutting out when hot and wonderin if I might have finally found problem.

[andy d]

bubbles mean that air is being sucked in some where. i would pop the inspection cvr under the left rear seat and eyeball the fuel outlet on the top of the tank right where the nipple elbows is where i had a leak.

[arter]

Thanks Andy. Pretty much what I figured. Put the glass filter in to check flow, saw rust and pulled and lined the tank. Still seeing air and wondering if it's an air leak (can only be from around the filter at this point) or if the high pressure pump is too much for my application and pulling air along with fuel. Have an AirSensor EFI system; 40 gal tank, clear low pressure filter, Holley Blue pump, NOS high pressure fuel pump, high pressure filter, to fuel rail and regulator. Figurin next step is to tighten connections, put low pressure filter before glass filter and low pressure pump and see what it does and looks like. Thanks for the come-back.

[Bob Barry]

At low fuel-pressure and low-flow, bubbles will naturally form. If the bubbles don't go away when you rev the engine up, then you may be drawing in air in the line, but if they go away, then it's just normal (my clear-filtered cars have done this).

[arter]

Thanks Bob. Gonna fill the tank up and see what happens, got about 1/4 in there now. Think the fact the pump might be slightly higher than the fuel level at 1/4 tank full would make a difference?

[AMX factor]

Another source might be the fuel pump itself. The bearings on the shaft can wear allowing air it at that point or the vanes themselves could be worn or nicked which can cause cavitation which adds air downstream. You can get a rebuild kit for less than $20 for that Holley.