I have my kicker (Honda) fuel line piped off of a
multi tap manifold type fuel/water filter and of course, the main motor (Merc) is tapped on same filter out manifold. (i.e., both motors share the same fuel filter that is fed by the tank) Both lines run from the manifold and run to/through their respective bulbs then on to their respective motors AND if my kicker's (Honda 9.9, 4 stroker) carb goes a bit low/dry (sits for a week, whatever), the main motor can/will suck air back through the Honda's carb.
This occurs because the Honda's fuel float's needle valve is open due to low'ish fuel in bowl AND the primer bulbs aren't necessarily always the best in class check valves. Especially true if the bulbs lay on their sides as they always do (on my raft anyway) and because the bulbs sorta just lay in and flop around in the motor well, and even after replacing them a few times over many years, they don't seal so tight always. New or old...............
Recalling that primer bulbs tend work best oriented vertically when priming in order for the check valves to position themselves optimally. I use only OEM quick silver/merc bulbs BTW. Wimpy check/return springs? IDK!!
I found this out because I have clear fuel lines in my main motor, it was running funny one day on the muffs and I saw I had a steady bubble stream coming in (panic insued). Pumped the Honda bulb tight hearing the Honda's carb bowl taking on gas, then no more bubbles......Go figure.
This didn't happen all the time I don't think but, it happened non the less. This spring I'm installing redundant
inline check valves, during bass season I just don't use the kicker all that much so it ends up drying up a bit.
