Yamaha 115 hp starter only spins

[pstephens46]

Here is a great response from Rodbolt on a similar issue in my opinion and I learned a valuable lesson:
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Old 05-01-2016
rodbolt17 rodbolt17 is offline
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Join Date: Dec 2010
Location: KDH NC
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you don't understand how to use that meter.
its very simple.

your looking for a voltage DROP not battery voltage.

at the + battery TERMINAL not cable attach one lead using the DC scale. the other lead will go to the + terminal on the starter again the stud not the cable end.
turn on the key, you should see less than .5V,turn the key to start,should still see less than .7v.

now using the same autoranging DC volt scale attach one lead to the - stud at the battery the other to a good block ground.
turn on the key, you should see less than .5 V try starting it and you should still read less than .5v.

if the + wire reads more than .7V start backing up with the lead that was on the starter battery terminal IE battery switch's and such until it reads less than .7 while loaded.

if the - cable reads more than .5V start backing down the - cable looking for junctions and splices that may have failed.

what we are doing is finding the voltage DROP acrossed a resistance.

take the ground wire and visualize the circuit, barring any terminal junctions it is a straight piece of wire from point a (battery stud) to point B the ground wire attachment at the block.
the only resistance in a perfect circuit would be the resistance of the copper,very low.

now when we operate,or try to, the circuit we are using the electrical pressure,measured in volts, to force electrons(amps) down the wire.
if all is perfect the pressure drop from a to b will be a minimal loss maybe .5V or less.
now if we have a bad spot in the cable(a resistance) we may drop 5-8 or more volts ACROSS that resistor.

loose corroded cable to terminal connections can act as a resistor as can bad cables,bad cable to cable end or any junctions between point a and b.
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[rodbolt17]

if ya gonna tinker with a motor ya gotta buy some tinker toys.

its that simple.
a basic digital meter can be had for 25 bucks or less.

[Taylodp1]

I took SCOTTCMB1965's advice and unbolted both the input lead and output lead from the starter relay and bolted them together. I touched the positive lead to the battery and the bendix engaged the flywheel. I then put everything back together in its normal position and GUESS WHAT-- I turned the key and the bendix engaged the flywheel. I then hooked water up to the motor and it started up. I am completely baffled as I had disconnected all those leads when troubleshooting this problem. I have absolutely no idea where the problem was. It is kind of scary because now I have no confidence in the boat. I would hate to get stranded 10 miles offshore. I think for the time being I will run in the river and close to home. Anyway, THANKS to all who have posted. Not only did I learn some things but I think others may have also. And I will buy a multi-tester and learn how to use it. Thanks again everyone.

[99yam40]

either you cleaned up a connection by taking them apart and putting back together or the start relay decided to make good contact inside

meter would have showed where the loss happened

[TownsendsFJR1300]

When my starter relay failed I got just a click about 5 times(no crank). Once I pulled the hood to investigate, it started and wouldn't do it again.

The relay, as posted above, was toast.

For the Op, I would just make up a short stout piece of wire to use as a jumper and keep it on board in a safe place. That'll get you home...

[Taylodp1]

Townsends, that is a good idea. Thanks.