Replace the entire fuel line, primer bulb, filter etc. Rubber and plastic degrade over time. The volatiles that make it flexible “evaporate” and leave the rest of it brittle and/or crumbling. It may look fine on the outside but a mess inside. Crumbly nuggets of deteriorating gas lines will plug up the line and cause what you are experiencing.
Completely agree with the quote above and will add, ethanol blended fuel is REALLY tough on older fuel lines and exacerbates the above.
