This is my first pontoon experience and also my first Yamaha outboard. I have a dumb question. When I push the throttle foreward to 3/4-full and let go of it, the throttle returns to almost neutral. Kind of like the old motorcycle throttles used to do. If I want to run wide open I have to hold the throttle forward the whole time. My other boating buddies have never had an engine to do this. Is this normal or does it need an adjustment? I bought the rig used. Thanks.