troubleshooting help ox66 before I take it to the mechanic

[MacIntosh]

Hi folks,
I did a quick search but didnt turn anything up on this site, so wondering if someone might help me troubleshoot a little—I’m not a mechanic and wont be able to do much, but if it’s a simple fix or something I can check I’d prefer to try that before I drive an hour to leave my boat with the mechanic for a few weeks.

2003 yamaha ox66 200hp. I’ve owned it for several years and it has always run pretty flawlessly. It's always had regular routine maintenance, has newer gas lines, etc so I believe it's in good running order aside from this.

Thursday night after fishing, it stalled on me twice while backing off the dock to trailer my boat. It has never been what I would call ultra smooth at idle, but always run consistently at idle, so I noticed it and decided to note it the next time on the water.

Monday, next time I ran it, it started like always—first turn of the key, fired right up and idled fine. Ran it a couple miles to fish, then another mile or so, then another mile or so, then a couple miles back to the ramp. At the last spot we fished, I turned the key and for a second there was nothing—I think I heard something move like the starter motor was straining but not spinning, so I knew the engine was getting juice but it didn’t turn over. I don’t recall if I turned the key again and it started, or if that was just a “pause” and it started—but it fired up fine and ran fine back to the ramp. When I went to drive the boat up onto the trailer, it would not start. It made a noise so I know it was getting juice, but it sounded like the starter motor wasn’t turning, just “straining”, and it didn’t turn over. Shut down graphs, turned off the power switch to my talon, checked starting battery connections, tried it a few more times, same thing--it would not start. Voltage at this point read 11.4v at the dash—haven’t checked this in a while so not sure how normal that voltage is, but it’s a relatively new battery and I’ve never had any issue with the battery after half a day fishing like this.

I dont know if the noise I heard was the starter motor or the fuel pump, but suffice to say I heard something from the motor, but the starter motor was NOT turning--if anything it was "straining", but the engine was not cranking.

Brought it home and charged up the batteries, and there she sits. Anyone have any ideas on what to look for/what to do to troubleshoot this?

[21XDC]

Sounds like a weak or undersized battery.

[MacIntosh]

Perhaps, but this is the first time this or the same size battery has failed ever, and it didnt get progressivly weaker it simply failed suddenly. Wouldnt a weak battery start getting weaker over time (crank slower, etc)? This one “strained” as described and then a second later cranked normally.
I guess its easy enough to try a diff battery and see if it makes a difference.
Thanks

[JoeFriday]

Could be the starter going. Don’t see them fail often, but I had a buddy that had his go. I got to handcrank his motor when his failed. Not fun, but you can hand start them. If you have a starter rebuild place around, you could pull it off and have them test it. Other thing to check before that is how the terminals from the battery to the motor look. If there is a patina, polish them to shiny brass and check it. When you changed the battery, you disturbed the connection. If the terminals aren’t clean, then it’s not getting a good connection. Had that happen to me when I swapped batteries.

[John Hagins]

Check battery connections, make sure they are not only tight but clean and the wires are secure in the connectors (on the battery AND the motor!!)

John

[triton]

Sounds like your battery went bad or you have more draw bringing down your battery....11.4 v after running is low, check the volts after charging you need a least 12 v to
start which is what I have always been told..

[98skeeter202]

Try set of jumper cables to see if it changes anything.

[ChampioN BASS]

Had simmilar on 225HPDI, found flex Batt Cable inside tube to motor half broken due to tilting motor, puting strain on cable and started breaking stran by stran.
To thin cable can't handle Cranking Amps.
Jumper cables will identify if it is the problem.
Good Luck.

[1ranger487vs]

don't forget to check your grounds to

[MacIntosh]

I finally got some time to troubleshoot this. Turns out it was the battery—I’ve never had a battery go south on me so quickly, but it went from “fine” one day to not holding a charge at all. I’m lucky I didn’t get stranded miles from the launch! New battery, and all is right and good in the world. Thanks for the help!

[21XDC]

[joebone1]

that's how batteries go bad - i've had 4 starting batteries work flawlessly until they didn't. I even had one go bad in the parking lot of our local farm & fleet, so it was easy to replace it.