air bubbles in inline fuel filter

[bpeters2]

85 300td: There is numerous air bubbles in my inline fuel filter. When I rev the engine it gets worse and is almost like a foam, when you return to idle tohe foam also gets better. I should note, that this car has a frybrid WVO conversion, so the diesel has numerous connections which could be "leaky", do airbubbles indicate a air leaks in the fuel system?? thanks for the help

[Hatterasguy]

I had the same problem with the SDL a couple of years ago, turned out to be a batch of bum filters. I had like 2-3 that did it, all bought at the same time. I figured it was the filter by swapping some clear hose in between the fuel pump, and hard line coming from the tank. Give that a try just in case you have a leak downstream.

[larry perkins]

when i see bubbles in the pre filter,after checking for leaks(wet lines and fittings)i go straight to the tank screen,i believe the vac created by the fuel pump will pull in air around the clamps if the strainer gets to stopping up.
larry perkins

[barry123400]

Same might apply if tank vent was blocked and too much vacuum in tank. Loosen fuel cap and look.