I always put my primer ball close to the motor, and they work out great for me. Never had a problem, and I had some tanks that were farther away than 10 feet from the motor. I think if it's too far away from the motor, and closer to the tank, it would have a harder time sucking the gas up and pushing it all the way into the motor when you want to prime the fuel line & carb.
Well, the motor doesn't care. BUT if the primer is close to the motor, it has to suck all that air from the hose before getting any fuel (assuming of course that it is empty). On the other hand, close to the tank, it gets fuel very quickly. But that is impractical where the tank isn't readily accessible. Or anywhere in between. Your preference.
They probably put the Bulb close to the Tank during manufacture so it wouldn't be flopping around if the Hose were to unwrap itself when the tank was being carried. Most pumps are better at pushing fuel than trying to evaluate the Hose of Air so Atmospheric Pressure at the tank can push the Fuel down the Line
The only time it will make a real difference is if the motor's fuel pump goes out and you need to manually pump the bulb to keep going. Put it where you can reach it while underway.
The only time it will make a real difference is if the motor's fuel pump goes out and you need to manually pump the bulb to keep going. Put it where you can reach it while underway.
Those primers have a couple of check valves in them, that's how they work. When you set it up, doesn't matter where you put it, but if you're able to hold it vertical while priming, you'll find they work heaps better.
