Was it working previously? Are the hoses hooked up correctly? The hose from the fuel filter hooks on the bottom of the carb, not at the push button. The base of the primer bulb plastic has a one-way valve in it that may be varnished shut. It's about 1/4" in diameter and brass.

Could your fuel filter, found at the end of the tube in the fuel tank (that's where mine is) be clogged and need replacement? You could try pulling the hose out of the tank with some forceps or needlenose pliers, remove the filter, put the hose back into the tank, and pump the bulb to see if it draws fuel into the carb. If that works, contact Mantis for a new filter. Don't till without a filter cause you can get dirt in the tank and clog up the carb.

Replace priambulb base that will fix it