Thanks for the explaining the low pressure suction mechanism.
As an experiment I loosened the lid on the pump basket to create a leak and did run the pump for a moment. With this setup I observed a pressure drop to 4-5psi on the filter gauge, lot's of bubbles in the pump basket and a the water making a washing machine sound. Did not look like it resembles my previous low pressure problem. After tightening the lid again the pump basket is clear of bubbles. I think this makes it unlikely that my original problem was an air leak in the supply line?
As an experiment I loosened the lid on the pump basket to create a leak and did run the pump for a moment. With this setup I observed a pressure drop to 4-5psi on the filter gauge, lot's of bubbles in the pump basket and a the water making a washing machine sound. Did not look like it resembles my previous low pressure problem. After tightening the lid again the pump basket is clear of bubbles. I think this makes it unlikely that my original problem was an air leak in the supply line?