Yamaha 115 hp starter only spins

[Taylodp1]

I have a 1999 115 hp model C115TLRY that will not start. The starter was only spinning and the bendix wouLd not engage to the flywheel. I replaced the starter and still the same problem. The battery tests good but is over 5 years old. I tried using a car battery to "jump" it with the car running but still the same results. I have cleaned the terminals and checked all the fuses. I'm suspecting the starter relay but am open to any suggestions.

[ausnoelm]

Bit strange it does it with the new starter too! I guess before you go too crazy, you could just spray a bit of WD40 on the bendix "just in case" but it sure doesn't sound like it is the problem if you replaced the starter, just a thought, did you replace the battery, or just muck around with jumper leads? if you used leads, I would try with a known good battery, properly installed as it should be.

[Matthew C]

You need to check your battery first. If it still does it after you put in a known good battery, do a voltage drop test at the starter. Chances are slim that you have 2 bad starters.

[Taylodp1]

Thanks to both for your prompt replies. I do plan to buy a new battery in the next couple of days and see what happens. I will post the results.

[Reel Kahuna]

Before buying a new battery, bring your existing one to O'reilly or Autozone and have it tested. If it's good then check your cable connections for corrosions. No need to throw good money after bad .

[Taylodp1]

I had the battery tested at Autozone and it tested to be good. There is a starter relay on the motor. Does anyone know that if that part was bad, is it possible that there would not be enough "juice" to allow for the starter bendix to fully engage?

[TownsendsFJR1300]

Here's your starter relay, part #6:

1995 C115TLRT Yamaha Outboard ELECTRICAL 2 Diagram and Parts

Here's the relay itself:
http://www.boats.net/parts/detail/ya...941-00-00.html

Try running a temp 12 volt line to the "output side" of the relay. (IE 12 volts line direct to the starter bypassing the relay).

It very possible the relay contacts inside are burned up NOT allowing the full 12 volts to reach the starter..

You can also confirm this with a volt meter on the same terminal when cranking. It should show the same voltage coming out as going in. Hopefully, you have 12 plus volts going in and then coming out to the starter... I suspect you don't

[pstephens46]

How does the bendix work? Does the electric motor have to spin above a certain rpm to force the gear to engage the flywheel?

[robert graham]

Manipulate the bendix with your fingers to ensure it's free to spiral up to engage the flywheel teeth....a drop of oil on the plastic helix can keep it moving freely...

[TownsendsFJR1300]

How does the bendix work? Does the electric motor have to spin above a certain rpm to force the gear to engage the flywheel?

Looking at his parts fisch (alone), I don't see anything to force it upward, so I'd have to agree with your statement ^^^.

I've seen starters with a curved spline, if you would, that the starter gear would rise up / out and engage when spun.

Being he's on starter #2, checking the voltage before and after that relay should tell the tale... There's not much else it could be....

When my starter relay quit (very different looking than his), you could hear the distinct click (the solenoid moving the disc worked fine) BUT, half the contacts were burned up (see below pic) and wouldn't even spin or try...

These are my starter relay contacts after I cut the relay apart:

[Taylodp1]

Townsends, thanks for your reply. I will try that this week-end and post the results.

[rodbolt17]

at least you will have a spare starter.

I would do a voltage drop test on both the + and - battery cables.

if you don't know how to do a voltage drop test do a forum search.
it has been beat to death.

DC electric motors are almost instantaneously at speed if supplied the correct voltage and current.
the bendix works on inertia.

remember the dude that gave us newtons laws???

as the starter shaft is going to spin almost instanty at the correct speed, IF supplied with the correct voltage and current, the inertia(body at rest) tends to make the drive sit like a bump on a log and ride up the curved shaft splines.

so fix your supply issue and go boating.

[robert graham]

at least you will have a spare starter.

I would do a voltage drop test on both the + and - battery cables.

if you don't know how to do a voltage drop test do a forum search.
it has been beat to death.

DC electric motors are almost instantaneously at speed if supplied the correct voltage and current.
the bendix works on inertia.

remember the dude that gave us newtons laws???

as the starter shaft is going to spin almost instanty at the correct speed, IF supplied with the correct voltage and current, the inertia(body at rest) tends to make the drive sit like a bump on a log and ride up the curved shaft splines.

so fix your supply issue and go boating.

Great explanation!...so that metal piece at the base of the helix gear is a Weight that provides inertia(body at rest)....I'll admit to not ever really understanding how that thing worked!....a lightbulb over the head moment for me!....leave it to Rodbolt to clarify how stuff works!

[TownsendsFJR1300]

Great explanation!...so that metal piece at the base of the helix gear is a Weight that provides inertia(body at rest)...

I mentioned the splined shaft in post #10 above, however W/O seeing it (or another), its not visible in the parts fisch..

[rodbolt17]

if the starter motor starts slowly IE: low supply voltage or low current the bendix will simply spin with the shaft.
to make it ride up the shaft the inertia of the bendix must be greater than the rotational speed.

it is how some folks can yank off a table cloth without upsetting the place settings.

if the shaft comes up to speed BEFORE the bendix gets a chance to start rotating, it goes up and then spins.

if the shaft comes up to speed slowly the bendix turns with the shaft and sits like a bump on a log.