Air bubbles in fuel line

[summers1996]

Just rebuilt 89 Suzy DT55 after a hole blew thru the center of the No. 2 piston. Engine now starts up fine and runs reasonably smooth. Now I see alot of air bubbles on the inlet side of the fuel pump and exiting the pump to the carbs. Could this have caused the hole in the piston (causing a lean condition)? My guess is the air is leaking in from the tank or supply fuel line/primer bulb. Old tanks and old fuel lne/primer. I will replace the fuel line/primer and re-check. The fuel tank is full. Any pointers or suggestions?