Could even be a bad fuel cap not venting, crack it and see if it flattens the primer bulb.
If it is the fuel line, you need to get the line out of the fuel tank to see if it's plugged. This line is behind the hydraulic pump under the cab. There will be two lines, one in one out.
I have had fuel that was full of algae, it was really bad and clogged the strainer. You can't push air down as it has a one way valve, so it needs pulling out