Yamaha V8 surging
 

Hello everyone. New member here but not a new boater. I recently purchased a 1993 Mariah 2200zc and couldn't be happier with it. It was a one owner boat with 900 hours on it. The boat is in Immaculate condition and ran great with the ears on the outdrive when I inspected it before purchasing it.

The first time I took it out I did the classic mistake of filling it up with too much gas and had it spit back at me. We took it out and it immediately started to Surge which led me to believe the gas filled the vent hose and wasn't allowing fuel pump to do its job. We drained 15 gallon from the tank and cleared the vent hose. But then when we went out yesterday it ran great for the first hour or two and then went right back to the surging problem. It started out at 3,000 RPM and would surge down to 2200 RPM. Eventually it got worse and worse, we were only able to run the boat at 1000 RPM and it took two and a half hours to get back to the launch which should have only taken 25 minutes.

When I would put the boat in neutral and give it throttle it had full response but as soon as I put it into gear it wanted to misfire and start surging right away. Has anyone else run into this problem? The mechanic I usually took my boats to continues to say it's a vent hose issue but I don't think that's the case. I blew into the vent hose while we were on the lake yesterday and there were no obstructions from what I could tell.

Thanks!