its a mercruiser 1998 5.7 efi serial #0L012408, the issue is engine starts fine from cold and can run for a while with no issues but at some point after 20 min-45 min or more its starts hesitating and dies completely. If engine is warm it will not start unless i wait for engine to cool off. I installed to new engine compartment blowers and run constantly, i doubt temp in bilge too high, Its a fuel cooler no VST. But again, my question is: is there suppose to be a pocket of air in the line between tank and filter??