['97ventureowner]

Welcome to AF!
They make a rubber nipple to go on the end of an air blow gun that attaches to your compressor line. I've used that setup in the past to check for a clogged line, or for an obstruction. I've never done a fuel line though. I would have to say though to be safe and not cause damage to disconnect the fuel line from the pump, and the top of the fuel tank. You don't want to blow something into the fuel tank and damage the pickup. You also might want to check the pickup inside the fuel tank. It has a screen on the end and sometimes over the years crud including rust particles can end up blocking the pickup, preventing a good fuel flow to the pump. It's been 30 years and I'm sure over the years debris has found a way into the tank if it's never been apart.