Well I'll chime in as well, another 853 with a fuel problem. My bulb was missing when I got the machine so I used one from my outboard engine/tank and worked for a while. Would only run for a short period then die. I couldn't get any fuel to come out of the bulb. Then I thought maybe the lines were reversed so removed the return line and fuel started pouring out, so I made that the supply line and connected the other as the return. Ran fine for a few months then last week the machine stopped dead after a half hour of running, full tank of fuel, and again, disconnected the bulb, nothing came out, pump pump pump, nothing. Swapped the lines again and fuel started flowing out of what I now had as the return. Jeez!!??
So, how can I tell which line is which, and where is this check valve you are talking about? Also, where is the pickup tube and hose connection? I can't seem to find it on my machine.
Thanks guys.