What causes primer bulb not to prime?

A primer bulb may not prime due to several reasons, including a clogged fuel line, a dirty or faulty carburetor, or an air leak in the fuel system. If the fuel tank is empty or if there are blockages in the fuel filter, it can also prevent proper priming. Additionally, if the bulb itself is damaged or cracked, it may not create the necessary vacuum to draw fuel effectively. Checking these components can help identify and resolve the issue.