Hey Nick,

Here’s something I noticed a while back on my boat. When I flip the exhaust switch while the engines are off, sometimes the flapper on the port side does not open. However, when I flip the switch while the engine is on, the flapper always opens. I imagine the pressure from the exhaust and water pushing against the flapper helps to open it. At any rate, you may want to check your setup. You may be running with one of your flappers closed (at least part of the time) without your knowledge. If so, this would account for one side having more soot than the other side.

On my boat, it’s always the same flapper. Perhaps the relay on that side is weaker than the other, perhaps that side gets less electrical current than the other – who knows? To me it’s no big deal. I just start the engines with the flappers closed. Then once the engines are running, I open them. If I happen to start the engine with them already open, I just bounce the switch off then on. It’s better than taking the boat back to the dealer for them to fix since they are incapable of fixing anything.

Thanks 29 Outlaw!

I never thought to check that...I mean, they seem to work properly. I wouldn't imagine that it would stay shut, though, at higher rpms when the solenoid isn't actively keeping it shut(switch on open-solenoid un-powered).