Engine backfiring/idling rough

[MrShelley]

Had another close call at the lake today.

Started the boat (2005 SANTE/Excalibur) to back it off the trailer and noticed it was idling a little rough. No worries, it's just cold. Dropped it in reverse, the idle improved, and pulled off the trailer. Dropped back in forward to ease over to the beach and again the engine was idling rough. Curious, I turned out onto the lake and gave it some gas. SEVERE rough idle, backfiring...simply would NOT accelerate. Immediately eased back to shore and popped the engine cover. Nothing seemed out of the ordinary.

I figured it had to be something with the transmission since the engine idles and revs fine in neutral and reverse. Noticed there was an electrical connection on top of the tranny with slightly corroded contacts. Popped the ring terminals off, cleaned 'em and tried again. Same thing. Out of curiosity, I tried starting the engine with these contacts disconnected. Wouldn't start. Hmmmm. Held the two wire ends together (bypassing the thing they connect to) and had my friend Steve hit the ignition. Busted right off. Idles fine, accelerates cleanly. We rode the rest of the day. I'm sure I need to reconnect whatever this thing is, but I'm betting it needs replacement. See the attached picture. What is this? What does it do? Where can I get one?

[AirTool]

It is the neutral safety switch and completely unrelated to your acceleration problem.

If your acceleration problem continues, the first thing I would do is remove the distributor cap and clean it and the rotor.

If it doesn't continue, it might have been random fuel issue that worked itself out.

[Quinner]

Cap and Rotor would be a great place to start. If they are original I would simply replace them.
Tool may be able to confirm, believe the Cap and Rotor can be had at your local Napa (or any quality parts store) as they are not marine specific.

[MrShelley]

Neutral safety switch. I didn't even think of that! I was looking at the tranny thinking "Why in the world are wires going to this thing?". I feel like an idiot.

I'm gonna chalk the poor acceleration and backfiring up to a fluke fuel issue. Like I said, the boat wound up running great all day!

Thanks for the valuable input guys!

[Quinner]

Had a similar issue and thought it was fuel related also, turned out to be the cap/rotor, when I checked them was surprised how bad they looked plus it ran fine all other times. From what I was told, that generation cap is know to have issues.

[riverrat0612]

Most likely the problem. While you are at it you might want to change out the fuel filter as well.