Electrical Problem?

Took the family up to the lake Sunday, boat ran fine all day until time to head back to the ramp. Boat started up fine, went into gear but, upon attempting to accelerate, it started running really rough. I throttled back and it ran fine, only making about 5 - 6 mph. I then noticed that my tilt/trim would not work and my gauges were not working either. We limped back to the ramp and I was able to get the boat trailered.

Took a look at everything yesterday and upon examination, found the connections and the fuse at the the fusible link (between the battery and the motor) were somewhat corroded. I cleaned them off, put everything back together and started her up. All gauges were working and the motor ran great, even as I increased power. This is a 2003 70 hp Yamaha 2-stroke. I am not all that knowledgeable about boat motors, can someone tell me why a bad electrical connection caused the motor to run rough? I am trying to learn all I can, thanks!

Like most electrical systems, they are in a loop of some sort, and if a portion has a bad connection/too much resistance, things do not operate fully/smoothly. Kind of like choking out everything at once.

23 Sailfish and Chris V helped me on a lot of electrical problems…they all seemed to happen at once. It turns out, that disconnecting, cleaning and re-securing all my grounds fixed most all of them. If it wasn’t a bad ground it was, just like you described, a corroded connection that just needed to be cleaned and at times you may have to replace the terminal/splice.
Just like you had to take that fuse out, clean it and reinstall…I have had to make it a regular routine to disconnect my battery, clean all terminal ends/battery terminals and put some of that dielectric grease on it. I am learning as I go just like you. I have done a lot of preventive mx and trouble shooting, mainly electrical but when something goes wrong that is when I learn the most

“Seahawk” 204CC Angler, 150 Merc

Being a novice/intermediate boater, I am still learning about outboards. It definitely makes sense if you have a bad connection everything requiring power is going to suffer. I guess I just never thought about the plugs not getting enough juice to burn all the gas I was trying to dump on to them. It was as simple as cleaning a couple of corroded connections. I will definitely be more vigilant in checking all of my connections.