I don't trust a lot of the rebuild kits I see. You don't know how long they've been sitting around. Certainly Ethanol can wreak havoc with the diaphragm and gaskets if they aren't compatible. It's easier just to buy a new pump. It depends on where the cam eccentric is on how easy it is to install. If the eccentric is in the right place it's a snap. If not you may have to turn the crank slightly or press down on the pump to get the bolts started.