i have a 1961 18hp Johnson model FD-15. i was trying to start this motor i just rebuilt that carb. i noticed that no gas was getting to the carb. i have a pressurized tank and i prime the bulb before starting. it seems like its not getting past the fuel filter. should i start by replacing the fuel filter and if so were can i find old fuel filters for this model. the fuel filter is a 376836