@Shern - I have noticed a very small amount of bubbles at the suction side, but far more comes out from the banjo bolt. IMaybe the suction side bubbles could have been cause from the return flow air? But mind as well rule that out too. I agree it could be a pin hole or maybe a tank fuel line. The tank screen could be completely clogged up, causing the pump to be fuel starved too. I remember some rust particles in the primary filter. I'll try bypassing the fuel tank and have it run off some diesel in a plastic bottle in the engine bay and see how that works.

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Theseus

Instragram: doss_project
1984 300SD - 930 Blue, OM 617
Murfreesboro, TN

Theseus owned a ship in Greek mythology, and when a part of the ship needed replacing, it was replaced. Eventually, everything was replaced. Is it the same ship? (I own the car of Theseus. )