I have a Sears Gamefisher 15 hp, 1990. I tried locating a fuel pump dia and a primer buld through Sears with no luck. Am I doing something wrong? I gave the Model number of 255.581503 but comes up they can't find a model number like that. Where else might I get? I know Napa has Force parts, but the model number (Sears) isn't in their book, I looked. Just Force numbers. Is there a way of a crossover or something.