Yamaha F225 TXRD melted fuse

[DivingJunkie]

So last trip out, I noticed my voltage was dropping on my gauge .I was only a few miles from the ramp so I just heading in. By the time I made it to the ramp my gauge was flashing 8 volts. When I got the boat home and starting checking the fuses, 1 fuse had completely melted to the housing. I removed and replaced this fuse and after charging my batteries I started the engine up to see if it would blow. It did not and my gauge seems to show a little high voltage 14.6. So I figure my next step is to Test the rectifier. Looking in my service manual it calls for a peak voltage adapter, my question is why do I need this? I thought the output off the rectifier is DC? Manual states 13V anything over and replace rectifier. Anyone know where to find the fuse holder without buying a new harness?

[boscoe99]

What manual says to replace the rectifier/regulator if the voltage exceeds 13 volts? I doubt that it is a Yamaha manual.

Normal Yamaha output voltage is more or less 14.6 volts. Many smaller HP models have over 15 volts output.

Input AC voltage to an R/R is measured with a peak reading meter. Output voltage from an R/R is measured with a DC voltmeter.

[DivingJunkie]

Boscoe,

I’m looking at Yamaha LIT 18616-02-76, I attached some snapshots of the charging section and test procedure.
I agree with your comment on the output which is why I asked as I would have thought the manual would have listed a range. Just trying to figure out what caused the fuse to melt. Not a fan of just replacing and calling it could without trying to figure out what caused it.

[fairdeal]

Although it makes no sense -
the 2003 F225 SM does seem to say to measure the "peak voltage"

as far as replacing it, if the output is >13 volts
IMO it is easy to "mis-read"

Measure the Rectifier Regulator output peak voltage. ....
Replace the Rectifier Regulator if the output peak voltage of the stator coil is above specification.


here's the test r/r section

[DivingJunkie]

I see that now....so this has me scratching my head as I may not be understanding what it is telling me to do. This is saying if the stator coil has high reading to replace the rectifier. With that comment why even check the rectifier

[fairdeal]

I suspect,
Yamaha believes it unlikely that a R/R would fail in such a way as to deliver "too high" voltage
that's why there is a "minimum" specification - 13V
but no "maximum".

And the test procedure is saying, if you test the R/R and the voltage is under 13,
that may be the fault of the stator coil -
but if you then find the stator coil voltage to be OK - the regulator must be bad.

Getting back to your problem,
my own "feeling" is that a gauge reading of 14.6 on that particular motor is "high"
but I don't see it melting your fuse.

I wonder if you just developed corrosion of the fuse/ fuse holder contacts -
and normal current flow caused it to overheat.

[DivingJunkie]

Fair deal

Thanks, that makes sense. I’ll check the stator after I order the test cable.
As far as corrosion, it could have been. But not blaming that until everything else checks out. Lose connection/or corrosion does create heat.

As far as the 14.6. I’ve only ever remember seeing 14.2ish but that’s been under load not on the hose.

[fairdeal]

FWIW Yamaha says to check the stator if the voltage from the R/R is low - under 13
IMO there is no reason to check it...

Looks to us, that you said in your first post that you saw 14.6

gauge seems to show a little high voltage 14.6.

[DivingJunkie]

Sounds like I should chalk this one up to a fuse holder connection failure. Thanks for the support, I will replace and give it a trial run

[boscoe99]

If you have 14.6 DC volts from the R/R then the R/R is OK and by default the stator has to be OK.

[boscoe99]

Although it makes no sense -
the 2003 F225 SM does seem to say to measure the "peak voltage"

I no longer have a peak reading volt meter adapter. I suspect that you do. If you measure DC volts output from the R/R with your peak reading meter, how does it compare to what you see without the peak voltage adapter being used?

[99yam40]

Sounds like I should chalk this one up to a fuse holder connection failure. Thanks for the support, I will replace and give it a trial run

yep, too much current would blow the fuse, not melt the fuse holder.
bad connection causes heat

[FabricGATOR]

Sounds like I should chalk this one up to a fuse holder connection failure. Thanks for the support, I will replace and give it a trial run

A loose connection would create heat as resistance/ As I was reading I was thinking that electrical loads draw watts. Volts multiplied by amps equals watts. My rabbit hole was tracking that when your charging system failed, and as your battery voltage dropped (being consumed by the spark plugs and Garmin) That due to the watts requirement, that would draw more amps of the lower voltage electrons to compensate..... Then 99yam40 woke me up from my dream... fuse would blow, not melt the connector.

What fuse holder? The small blade fuse block or the main charge fuse chunk?
Pictures?
There are a few folks parting out engines on eBay Sometimes if you don't see what you are looking for, you may ask....

I hate the thought of buying a complete wire harness just to correct an electrical connector. That is why I hunted down Eastern Beaver.