I just finished this task with my 1963 Evinrude 40HP Lark. I know Johnson & Evinrude are similar, but can't claim I know they are identical so my response is based on Evinrude. The fuel hose was 1/4" ID, I used marine fuel line per my guru's recommendation. I measured that I needed 11', but bought 15' for security. I thought mine had 2 sizes as well, turns out one that comes out of the front of the engine between the carb & starter and goes to the port side of the engine is a vacuum hose. I took it to NAPA & got silicone hose to match (again per my guru). It was about 16-18", they only sell by the foot anyway. My fuel bowl has a wire cradle underneath it with a plastic nut. By turning that nut it loosened, and swung to the side, allowing the fuel bowl to drop. I was able to buy a fuel filter (looks like a little net bag) and a couple of replacement gaskets online. Took more hours than I expected, but hasn't been done in a number of years on mine (which my father bought new). I highly recommend you heat a cup of water in microwave to very hot, then soak 2" of the hose in hot water just before trying to install that end. It makes the hose end larger & softer, & much easier to get on. Also, getting one fuel line & the vacuum hose required removing the electric starter; that required loosening the bolts that hold down the manual starter so the electric starter would slide off the 3 studs that come out the starboard side of the engine.
Good luck, & please post whether this was accurate for your Johnson as well. May your knuckles remain uninjured...
