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Started By
Message
Outboard Engine Question for Those of You OBers Mechanically Inclined
Posted on 5/5/13 at 6:41 pm
Posted on 5/5/13 at 6:41 pm
So, I took the boat out on the bayou this afternoon for a quick run and to try some fly fishing.
I get out and notice the volt meter is high...as in 15, almost 16 volts (runs around 12 to 13 WOT usually)
Being rather surprised, I slow down and turn off the engine. I turned the power on (engine off) to see what the gauge would read...12 volts.
So, I'm thinking it's the alternator.
Then I turn the engine back on and drive a short ways and the gauge jumped back to around 15 volts. I turned on and off all switches on the boat and nothing changed.
I finally, tried the tilt which caused the volt meter to drop back down to 12. After adjusting the motor up or down, the gauge would drop to 12 and then work it's way back up to 15-15 volts.
What do y'all think is the issue?
Edit: The engine is a 2006 90 hp Yamaha two stroke
I get out and notice the volt meter is high...as in 15, almost 16 volts (runs around 12 to 13 WOT usually)
Being rather surprised, I slow down and turn off the engine. I turned the power on (engine off) to see what the gauge would read...12 volts.
So, I'm thinking it's the alternator.
Then I turn the engine back on and drive a short ways and the gauge jumped back to around 15 volts. I turned on and off all switches on the boat and nothing changed.
I finally, tried the tilt which caused the volt meter to drop back down to 12. After adjusting the motor up or down, the gauge would drop to 12 and then work it's way back up to 15-15 volts.
What do y'all think is the issue?
Edit: The engine is a 2006 90 hp Yamaha two stroke
This post was edited on 5/5/13 at 6:50 pm
4
Posted on 5/5/13 at 6:55 pm to stewie
Bad gauge or wiring for the gauge
Posted on 5/5/13 at 7:01 pm to Hammertime
When runnin put a voltmeter on the battery leads or the lead at your dash voltmeter
Thatll give ya the engine output charge
Thatll give ya the engine output charge
Posted on 5/5/13 at 7:02 pm to Hammertime
That's what I thought at first...so I turned on the power (w/o cranking the engine) and the meter jumped up to 12 volts, as it normally does.
It also bounces between 12 and 15 volts when I hit the trim/tilt.
Additionally, while on the water, I unhooked the battery, cleaned the terminals, and hooked it back up to see if that was the bad connection. Same problem.
It also bounces between 12 and 15 volts when I hit the trim/tilt.
Additionally, while on the water, I unhooked the battery, cleaned the terminals, and hooked it back up to see if that was the bad connection. Same problem.
Posted on 5/5/13 at 7:02 pm to stewie
I don't know about a boat alternator but in an automotive alternator, when a diode goes out they over charge and cook themselves.
Could be the same thing going on here.
Could be the same thing going on here.
Posted on 5/5/13 at 7:02 pm to stewie
quote:
I finally, tried the tilt which caused the volt meter to drop back down to 12. After adjusting the motor up or down, the gauge would drop to 12 and then work it's way back up to 15-15 volts.
Anytime a load is put on your power supply, there will be a voltage drop, especially something that pulls as much current as adjusting the tilt.
I would check to make sure none of your electronics would be affected by the slightly higher voltage. If not, just let the alternator do its thing.
If you put a volt meter on some of the outlets in your house, I doubt you would get an exact 120V anywhere. There are small fluctuations that do not make a huge difference.
Hammer could be right in that your meter could be bad, but I doubt it since you say the voltage returns to 12 after the motor is off.
PS I'm about to graduate in electrical engineering, so while I'm not expert, I feel I know a couple of things.
Posted on 5/5/13 at 7:08 pm to bapple
I agree with Bapple.
Although I'm not nearly an electrical engineer, I did stay at a Holiday Inn Express last night.
Although I'm not nearly an electrical engineer, I did stay at a Holiday Inn Express last night.
Posted on 5/5/13 at 7:08 pm to REB BEER
quote:
Although I'm not nearly an electrical engineer, I did stay at a Holiday Inn Express last night.
If those commercials are right, you are definitely qualified.
This post was edited on 5/5/13 at 7:09 pm
Posted on 5/5/13 at 7:09 pm to bapple
quote:
If you put a volt meter on some of the outlets in your house, I doubt you would get an exact 120V anywhere. There are small fluctuations that do not make a huge difference.
Yeah, I'm going to do this tomorrow (the volt meter is at the shop and I don't feel like getting it right now).
quote:
I would check to make sure none of your electronics would be affected by the slightly higher voltage. If not, just let the alternator do its thing.
All of the electronics worked fine while out there (but I didn't have the GPS or a few other things with me)
I started to worry a little because it started to get into the warning "danger" zone on the volt meter...and I didn't want to get stranded in the middle of the bayou by myself.
Also worried that it could cost a pretty penny to fix if it's an alternator or some type of power regulator that needs replacing.
I'm no engineer, much less an electrical engineer...so I'm more or less up in the air about what could be the issue.
This post was edited on 5/5/13 at 8:28 pm
Posted on 5/5/13 at 7:16 pm to stewie
quote:
So, I'm thinking it's the alternator
This. The regulator is shot. Must be a Merc. Had one do that on me once. Order one off ebay thru a shop in Fla for half price.
Posted on 5/5/13 at 7:16 pm to stewie
quote:
because it started to get into the warning "danger" zone on the volt meter.
I would bring it to a boat tech and let him check out your electronics. No point in running the risk.
Your electronics may not be affected but if the volt meter says "danger" there's probably a reason it's there. Better safe than sorry (or broke).
Posted on 5/5/13 at 8:24 pm to bapple
quote:
Your electronics may not be affected but if the volt meter says "danger" there's probably a reason it's there. Better safe than sorry (or broke)
My thoughts exactly...
I'm gonna talk to a local mechanic tomorrow and run a few more tests on it.
bust out another thousand
Posted on 5/5/13 at 8:26 pm to stewie
quote:
bust out another thousand
Nice. Never heard that one.
Good thing I'm not much of a fisherman.
Posted on 5/5/13 at 8:51 pm to stewie
You don't have an alternator. The stator assembly under the flywheel does the charging. The rectifier controls how much DC voltage is sent to the battery. Some motors have voltage regulators instead of rectifiers.
Posted on 5/5/13 at 9:34 pm to meauxjeaux2
quote:
The stator assembly under the flywheel does the charging. The rectifier controls how much DC voltage is sent to the battery
Do you think the rectifier/regulator is the issue here?
Posted on 5/5/13 at 9:47 pm to bapple
quote:
PS I'm about to graduate in electrical engineering, so while I'm not expert, I feel I know a couple of things.
All I know about lectricity is: Don't pee on a lectric fence and cats do funny stuff when they get into letric fences.
Posted on 5/5/13 at 9:49 pm to stewie
Too much voltage = bad rectifier/regulator.
not enough voltage = bad stator.
not enough voltage = bad stator.
Posted on 5/5/13 at 10:23 pm to meauxjeaux2
quote:
Too much voltage = bad rectifier/regulator.
That sounds like it...
I was reading on another forum that it could be a weak battery (a sign that the battery is about to die).
The battery I was using was from late '10, so I don't think that's the case...but it's always a possibility.
Posted on 5/5/13 at 10:33 pm to stewie
That is a possibility. The battery will need to be load tested to check its capacity. Not voltage tested,load tested.
Posted on 5/6/13 at 12:23 am to meauxjeaux2
quote:
You don't have an alternator. The stator assembly under the flywheel does the charging. The rectifier controls how much DC voltage is sent to the battery. Some motors have voltage regulators instead of rectifiers.
Damn Meaux. I had no idea this is how boats generated power. Like I said, I'm not much of a fisherman so I just assumed most outboards had an internal alternator but this is very interesting.
I just finished a machine design class where we did a ton of experiments with different synchronous DC motors. You seem to be a pretty knowledgeable dude.
Well played!
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