It is just as easy to overprime the engine using a primer bulb then it is to prime it by the choking method. Fuel filters are made of metal and most have single or double O-ring seals. The plastic primer bulbs leak where the "edge" (created by the molding process) is, and the silicone ones tear because they are fairly thin. Also, I've gotten pinhole leaks in them just by running in sand and dirt a lot.