Now you got me to thinking....I haven't found a priming pump yet. I have looked too! this is attached to the fuel filter and looks like a saucer sitting on top of a square base. You can actually see little sprays of fuel come out of it while it is idling. I'm NOt familiar with the 115 chassis and I don't have any manuals for it so I'm really in the dark here! Remember there is a hose that is the exact right length to connect to this thing. The hose is just laying there right now with a clamp still on it. Hose is about 3/8" I.D. ( excuse me) 10mm I.D. and is connected to a steel line that goes down under the vacuum booster. ( I haven't traced it past this point) all I did was make sure it wasn't a vacuum leak and nothing was running out in copious amounts.