Stator question

[Mulletman]

2002 Yamaha F115tlra. What might be symptoms of a failing stator?

[boscoe99]

A failing stator will result in insufficient voltage and/or current being made available to the rectifier/regulator. The battery won't be recharged and when it gets low the engine will run poorly or not at all.

[Mulletman]

Thanks. Sorry I took so long to reply but I've been out of town. I took my Yamaha F115 4stroke out for a test after numerous previous tries and it ran poorly at first, then took off and planed easily for about 3 minutes, Then it fell on its face again. Thought the stator might be the culprit. No codes thrown on YDS though. Tested injectors. One connector was loose. Reconnected it and tried today. Same results. Any suggestions.

[TownsendsFJR1300]

What is the voltage at the battery when the engine is running?

[rodbolt17]

the stator,other than charging the battery,has nothing to do with the ign system on that motor.
most likely its a fuel issue.

[boscoe99]

Thanks. Sorry I took so long to reply but I've been out of town. I took my Yamaha F115 4stroke out for a test after numerous previous tries and it ran poorly at first, then took off and planed easily for about 3 minutes, Then it fell on its face again. Thought the stator might be the culprit. No codes thrown on YDS though. Tested injectors. One connector was loose. Reconnected it and tried today. Same results. Any suggestions.

As noted, check all electrical connections for cleanliness and tightness. Particularly the battery cables at both ends.

Might want to check the fuel pressure to see if it is correctly maintained. Put a fuel pressure gauge on the motor. What is the fuel pressure when the motor falls on its face?

When was the last time the VST fuel filter was replaced?

Might want to have someone pump the heck out of the primer ball when test runs are being performed. Does the motor still fall on its face or does it now run well?

I am also thinking it is fuel system related problem. Number one problem issue for most outboard motors. Easy to say but tough at times to trouble shoot.

[Mulletman]

The fuel pressure is 40psi at idle and with a guage attached. The vst was cleaned last week. The battery voltage is 12.5 to 14. Replaced one of the ignition coils recently. Possibly the other failing? Also replaced the rectifier. Does the stator provide voltage to the ignition coils? Any more help is greatly appreciated.

[TownsendsFJR1300]

12.5 volts is somewhat low, about 85% (12.8 volts, the battery is fully charged).

Is that 12.5 volts at idle or NOT running.

At approx what RPM does it jump into at least the mid 13 volts, 14 volts?

That engine should be charging above 12.8 while its running.

[bajakeith]

Stator

The Stator does not "charge" the battery as one would think !! the stator Maintains the batt (charge) that's ALL its designed to do.....Ya want a batt charger ??? Buy one !! A stator is a small/weak electrical set of winding under the flywheel and nothing more.....anyone that would tell you otherwise does not know/understqnd electrical systems....GRrr...

[rodbolt17]

I will say it one more time.
the stator has NOTHING to do with spark on that motor.

the F115 uses a TCI 12V ign system .

go chase a fuel rabbit.

[Mulletman]

Ok. Thanks for some helpful advise. I've been chasing that fuel rabbit for a while now to the extent of completely draining the main tank, running on a 6 gallon tank, changing out the primer bulb and all fuel lines, cleaning vst, changing all internal filters and water seperator filter, new mechanical fuel pump. The high pressure pump maintains 38-42psi fuel pressure and all injectors cleaned and replaced. Where else could that elusive bunny be hiding?

[ausnoelm]

Other than the stator is not the issue in this case, Bajakeith, please explain how the boats battery gets charged!

[rodbolt17]

doesn't really "charge" the battery although it can some.
the engine eats about 7-9 amps just to run without hitting the trim.
the charging system only puts out 16-20 amps or so.
that only leaves 8-10 amps or so for charging.

if pushed to hard trying to charge a dead battery they can smoke rectifiers.

[boscoe99]

Some strange stuff can surely get published on the inner web.

Certainly the F115TLRA can charge a battery. Not very fast but it can do it.

Published output of the rectifier/regulator is 24 amps. Net output from the motor is shown as 16 amps. Which means that the motor is using nominally 8 amps or so to run itself. Whatever is left over (24 minus 8 = 16) is available to recharge a battery. 16 amps is much more than a number of auto store battery chargers output.

One can see this for themselves. Start with a half charged battery that is about 12.3/.4 volts. Start the motor and run it for several hours at 4000 RPM or better. Turn the motor off. Let the battery sit for a day. Next day it will more than likely indicate 12.7 volts, which is nominally a fully charged battery.

Now before someone jumps me, this presumes the battery is the size that is normally stated for use with the F115. If a size 8D battery is installed then all bets are off.

[bajakeith]

OMG again

At 12.6 volts a batt 50 percent discharged !! A outboard is NOT a battery charger !!! get it between your ears !! Hello......