yamaha 10hp strange thing

[tat]

Hello. This winter, my canopy tore and let in rain. I noticed the lid had come off my starter battery box and rain had filled it to totally submerge the battery (which also has a 40w solar panel attached).

I lifted the battery (standard sealed car battery) out, expecting it to be kaput, removed the terminal connecters, but it measured 13v. So I removed the solar connectors, put the outboard (1970s Yamaha 10hp) terminal connecters back on and turned the remote ignition key and instead of starting as it does every time, and just had done with the battery submerged, there was just a bit of a starter motor sort of whoosh click sound or something, but not a starter motor movement.

I removed the terminals and took a feed from the leisure battery (14v), but still nothing.

I took the engine cover off and measured at the starter motor and solenoid, getting a good voltage.

So what could be going on? I thought it would just start. Doesn't make sense.

I used the emergency starter cord, and it starts well enough.

So, I'm going to have another try next week.

Could i have damaged the solenoid? Should I try to fire the starter with a direct feed?

I do not know much at all re engine electrics. If you have a suggestion, please be as basic simple plain speaking as you can and consider me as a total beginner. Thanks. Doug

[Compass790]

You may have been better to post this problem in an electrical forum Doug but never fear, someone will be along to help you.
I will say though, just because your submerged battery has 13v does not mean it's any good. In fact I'd say in all likelyhood it's toast but I'll leave it to the electrical experts to troubleshoot your problem.

[Wotname]

The first and really only question:

What is the voltage at the starter motor / solenoid while cranking the engine?

Measuring the open circuit voltage is meaningless. You could put 8 AA batteries in series and get 12 volts (open circuit) but is ain't going to start anything.

[tat]

Thanks Compass790 and Wotname. I've had another go and will move to electrical section

[Bill O]

Doug,
Since the motor starts by hand, then you've eliminated that the motor isn't locked up.
From what you have provided, can't determine if you battery is basically dead (would fail a load test) or your starter may be bad. These are your 2 basic choices of why it's not working.

Would check the battery w/a load test or pull the starter off and quickly test the starter to make certain it is working. If the battery is good under on the load test then you will still need to pull the starter and test it.
Possibly lightly tap the starter motor, maybe it will work.

[tkeithlu]

Your description of the starter noises is not quite enough for me to think AHA!

A possiblity is the relay that the ignition switch throws in order to supply many many amps to the starter. Check it. Another is connections throughout the system. Starters need the amps. You can read 12.8v DC, but the connection is loose or corroded and will not send the amps to the starter. Check them all, particularly given that the circuit has been in water. Fine sandpaper clkeans them up.

Load test the battery. There are pretty good digital testers available now - I use one of these at work:

https://www.amazon.com/TOPDON-BT100-...607286&sr=8-10

but on the other hand, the old manual resistance coil types still will tell you whether the battery can take a load:

https://www.amazon.com/Battery-Tende...6607392&sr=8-6

If the battery is OK, then it suggersts that the Bendix gear in the starter is not flying into place. That's pretty easy to fix with some light oil. Take the starter off and clamp it in a vice. Ground the frame with a jumper cable, and apply volts to the positive terminal with the other jumper. The little gear in the front of the starter (the Bendix) should fly forward and spin like mad. Oil it and free it up if it is not sliding forward against its spring. Don't do this test with the starter not clamped; the torque is enough to throw it at you.

Given the water, connections and the Bendix are prime suspects. Your battery may be OK.

[GoneDiving]

It's pretty common for batteries to show full voltage when sitting but drop too low under load, especially so after it has been stressed As asked above, what's the voltage when the starter is engaged? 10v wouldn't be a concern but a drop into single figures means that it's time for a replacement.

Have you tried a temporary replacement just to test?

[Wotname]

Just to be clear, you don't need to load test the battery in so far as you are load testing the battery every time you start the engine.

Measure the voltage at the battery terminals while cranking - this will tell how good the battery is.

Measure the voltage at the starter motor terminals while cranking - this will tell how good the wiring/terminals are.