Boat Won't Start: Possible Electrical?

[Cbourgeois 1]

We keep our boat at a local marina & the last couple times I've went to use it, it appears that the batteries are dead and it won't start.  I have replaced both batteries and double checked all battery harnesses. Everything is good.  Yesterday, we were out on the boat for a few hours & as I started the boat to head back to the marina it would barely turn over.  About that same time, I had a small rattle noise coming from the engine compartment, just as the boat would go from idle into gear.  When I throttled up just a little bit, the rattle would go away.   It drove fine back to the marina, but when I got it back on the lift, I tried to start it again & it was dead.  I charged both of the new batteries the night before & then brought a battery home to check it & it's still nearly 100% charged.  When the boat is running the Volt meter is right at 13 volts. 

I had the belt & impeller replaced at the dealer this spring and now I am wondering if maybe the tech knocked something loose when he was working on my boat.  I am not good with electrical issues, so any thoughts would be greatly appreciated.  

Thanks

[InfinitySurf 302]

23 hours ago, Cbourgeois said:

We keep our boat at a local marina & the last couple times I've went to use it, it appears that the batteries are dead and it won't start.  I have replaced both batteries and double checked all battery harnesses. Everything is good.  Yesterday, we were out on the boat for a few hours & as I started the boat to head back to the marina it would barely turn over.  About that same time, I had a small rattle noise coming from the engine compartment, just as the boat would go from idle into gear.  When I throttled up just a little bit, the rattle would go away.   It drove fine back to the marina, but when I got it back on the lift, I tried to start it again & it was dead.  I charged both of the new batteries the night before & then brought a battery home to check it & it's still nearly 100% charged.  When the boat is running the Volt meter is right at 13 volts. 

I had the belt & impeller replaced at the dealer this spring and now I am wondering if maybe the tech knocked something loose when he was working on my boat.  I am not good with electrical issues, so any thoughts would be greatly appreciated.  

Thanks

When you say it wont start, what are the symptoms....does nothing happen at all when you turn the key (like throttle is not in neutral), or does it crank slowly but not enough to start, etc. (I know you said above that first time it would "barely turn over", but started... then at the marina you tried again and it was dead....does that mean nothing at all when key turned to crank? Did your gauges and fuel pump cycle when you turned the ignition on before trying to start it) Perhaps the starter is going out or does not have a good connection?

Where you floating for those couple hours and had the stereo on. Do you have a battery switch/selector so batteries are isolated so stereo only drains 2nd battery and not the starter battery when floating, assume you don't keep it on combine if you do have a switch.

Check all your ground cables to be sure they are not corroded and are properly torqued. I would check every connection in engine compartment as well as the fuses and relays to see if any corrosion build up, or perhaps something is loose and does not have a tight connection.

Far as the "rattle", did you check the belt to see if it has the proper tension since that was something that was replaced recently. If that happens again, I would open engine compartment and try to pinpoint the source since a rattle could be many things.

Above are just some guesses based on things seen/heard in the past, I know bad/corroded grounds or loose connections have caused many gremlins. @Wylie_Tunes is an electrical guru, perhaps he has better ideas.

[Cbourgeois 1]

Thanks for the feedback.  On the lift, when I say "dead", the boat would beep at a half turn on the key, but if I turned the ignition all the way (to start the engine), I would get nothing.  no clicking, no lagged-drained battery attempt to turn over.  nothing.  I double check all of the fuses & wiring connections and everything looks fine.  the gauges all work when the ignition is turned on, as does power to all ballast, & stereo switches.  I thought maybe the radio was draining the battery, so I unhooked it & isolated a single battery (that was recharged), and still nothing.  I'm now wondering if perhaps the starter is locked up & needs replaced.  Not sure though. 

[InfinitySurf 302]

Have you checked to be sure the throttle is in neutral and wiggled it? Its happened to many people (happened to me one day and I was freaking out till I realized the boat was still in gear), all functions will work but boat wont turn over and act like the battery is dead when you try to start. The neutral safety switch may be going out too, I hear you can jump the terminals to see if that is your problem but don't know enough about that to say for sure.

Since when you turn on the ignition you have power to everything else, it must be related to the neutral safety switch, the starter or an electrical or ground connection not getting a good connection, or a relay/fuse being out (there is a relay for the starter located in a fuse box on the top of my engine).