Help engine trouble

@Alex Smith. You may want to do a "post mortum" Whereas you had a 30 amp fuse blow previously indicates, to me, an overload condition rather than a dead short. A dead short would not allow you to replace the fuse. It is still possible you have a transient short such as a skinned wire but I'm betting on an overload such as a large stero/amplifier system that may have been in use at the time of failure or it just may have been as simple as an overheat of the rectifier.

We're the rectifier cooling fins clean and free of dirt and oil? Check the condition of the other one. The rectifier integrated circuit is actually pretty small, composed of dides to change the AC sine wave to a flat DC sine wave for battery charging. The battery will filter out any DC ripple for a clean DC source for your radio or other DC devices.

All of what you see, when you look at a rectifier, are cooling fins for dissapating heat. If those fins are blocked or dirty the rectifier can overheat and cause trouble usually just causing them to burn out. Hopefully we'll all learn from this.

I agree with Gym. When I look at your pictures the cooling fins don't look blocked up. Since you blew a fuse earlier this could be the culprit. I am surprised that the fuse didn't blow again preventing that much current from going through the rectifier. Glad you got home OK.

@Alex Smith WOW, that was a close call. I'm glad that you made it home safely. You're scenario raised a few questions in my mind. First, knowing that the 21' 2007 boats didn't come with one, do you have an aftermarket battery switch installed? Second, did you attempt to disconnect the main positive power to that engine before returning to the dock? It seems like the risk of fire would've been greatly reduced if you had a way to shut the source of power as soon as possible. I'm only asking because I usually boat at least ten miles from a dock and I'd love to have a mental checklist of how to handle this if I were in your shoes. Is there anything that you did or didn't do that you would recommend in the future? Thanks in advance for any advice.

Alex Smith said:

@ToddW850 that would be great thanks.

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I will get the info to you as soon as I return.

Guys... he's in Florida. Why aren't we all just headed down there to help?
Just Kidding! It's spring here, so it's boat prep time.
I think they are on the right track in that it's not a short, but something overloading it.
I don't know much about rectifiers, but if it's taking the current from the engine and making it a DC current and feeding that to the battery, then couldn't it be that there is something wrong with the charging system of the engine then? It's stators I believe, so if they wear out or break, what happens? Perhaps something like this? Would it be worth a look? I would hate to be buying a new piece of equipment just to have the underlying cause force you to go back into it again.

itsdgm said:

@Alex Smith WOW, that was a close call. I'm glad that you made it home safely. You're scenario raised a few questions in my mind. First, knowing that the 21' 2007 boats didn't come with one, do you have an aftermarket battery switch installed? Second, did you attempt to disconnect the main positive power to that engine before returning to the dock? It seems like the risk of fire would've been greatly reduced if you had a way to shut the source of power as soon as possible. I'm only asking because I usually boat at least ten miles from a dock and I'd love to have a mental checklist of how to handle this if I were in your shoes. Is there anything that you did or didn't do that you would recommend in the future? Thanks in advance for any advice.

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Update so far nothing found. Everything is stock no additional accessories added. No battery switch, no additional audio, no additional lights. Battery and connections seem to be ok. Currently trying to track all wires they seem to be in good condition so far. Going to hopefully finish inspecting all wires this evening and I guess next would be checking all charging components.

Sorry to hear about your dilemma. Does anyone know if other engine models have these same components? That could've been a very bad day. Glad you made it back safely and hope you find and are able to post a resolution soon.

Speedling said:

Guys... he's in Florida. Why aren't we all just headed down there to help?
Just Kidding! It's spring here, so it's boat prep time.
I think they are on the right track in that it's not a short, but something overloading it.
I don't know much about rectifiers, but if it's taking the current from the engine and making it a DC current and feeding that to the battery, then couldn't it be that there is something wrong with the charging system of the engine then? It's stators I believe, so if they wear out or break, what happens? Perhaps something like this? Would it be worth a look? I would hate to be buying a new piece of equipment just to have the underlying cause force you to go back into it again.

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I agree you need to check everything. I assume this is like most cars and yes a bad charging system could overload the rectifier. The rectifier could have simply shorted internally and as many electrical problems it can come and go.

I am curious, since there are two rectifiers there must be two charging systems feeding one battery? If this is correct it should be pretty easy to first check for shorts by comparing the systems (when isolated) and then once powered up to quickly check the output (amps and volts) to see if the charging system is working. If there is not a direct short this should not harm the new rectifier. Am I missing something here? I know the charging systems are not powerful like automobiles but I have not worked on mine at all and I hope to never have to!

I would also have the battery tested. If there is an anomaly with the battery, that should also be able to overload the rectifier.

Alex Smith said:

Update so far nothing found. Everything is stock no additional accessories added. No battery switch, no additional audio, no additional lights. Battery and connections seem to be ok. Currently trying to track all wires they seem to be in good condition so far. Going to hopefully finish inspecting all wires this evening and I guess next would be checking all charging components.

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@Alex Smith. Just speculation on my part but I looked closely at the picture showing the back of your burned rectifier. That round burned spot is the actual rectifier comprised of diodes. The rest is just cooling fins. The burned spot indicates, to me, where the problem began. I think your rectifier diodes just went bad, shorted out, drew too much current and overheated.

Update after checking all components, stater, and battery I had come to the conclusion it was just a bad rectifier. But then after taking a break for a trip to Disney I got back at it today. Now a new concern after taking the melted bracket off and putting the new one on. I then checked the stator again with the multimeter giving me a new reading. I went to start the engine and nothing. Checked all kill points and nothing, checked to the 30amp fuse. It had gone bad again.

Back to the drawling board. I'm going to put it in the water tomorrow and try to find out why this keeps happening.

Did you check the 30 amp before you replaced the rectifier? It was good when you started? I know it sounds obvious, but you would be surprised how many problems are solved with the obvious questions...

Besides, if your answer is that you started with a good 30 amp, I am afraid that I have no clue, other than that something is drawing way too many amps through the entire system, which is putting the weak point of the rectifier at risk. Only thing I can think is to unplug and start ohming out back through circuits until you find a short or a big overdraw.

Sorry.

@Alex Smith. Have you done or had ANY electrical work done? Added a 2ND battery, battery switch or stereo work? Does the 30 amp fuse blow immediatly when replaced or when trying to start?

Try disconnecting ALL wires from the batteries then reconnect ONLY the red (hot) and black (ground) wires to the affected engine. Try starting and running in that configuration to see if it runs ok without blowing the fuse. I would do this on a hose to minimize any potential issues on the water.

Another thing you can try is to measure the stator's AC output with an amp probe. Then you can compare that with the reading of the stator on the good engine. I'm not sure what access you have to the stator wiring though.

Here is a YouTube on a lawnmower stator & rectifier that may help to explain what they do and how to test for continuity aND shorts. It does not show how to test for current flow though bUT I thint your isue is outside of the stator.

If you have a multimeter you could check the stator coils. According to the service manual, you should see ~0.31 - 0.38 ohms.

More importantly you want to check continuity from the stator coils to ground as in the YouTube video I referred to. This will check for shorts to ground which could be causing your blown fuse. An open coil will only affect battery charging which could go unnoticed until the battery dies.

@Alex Smith here is the guy in Destin I used. Chris Poole, owner of Liquid Fix Racing, 225 Pelican Place, Destin. 850-685-3751. He's raced jet skis for many years and worked on the Yamaha waverunner engines.

During my issue, he called in a guy to help him. This guy is a certified Yamaha mechanic and will travel to you. Not sure if he'd come all the way to Gulf Breeze or not, but his card is below. Could be worth a call and see.

Let me know if I can help you out further.

When the rectifier on my 2004 fx140 Waverunner went out, it just stopped charging the battery but caused no damage and I was able to start the Waverunner without the rectifier installed run it without problem (after trickle charging the battery of course).

I cheaped out and bought a rectifier from SBT instead of Yamaha OEM, actually went through 3 of them before SBT finally got me one that worked and didn't overheat/not charge.... Taking away weeks of summer use. My lesson learned was to buy OEM parts even if twice the money.

ToddW850 said:

@Alex Smith here is the guy in Destin I used. Chris Poole, owner of Liquid Fix Racing, 225 Pelican Place, Destin. 850-685-3751. He's raced jet skis for many years and worked on the Yamaha waverunner engines.

During my issue, he called in a guy to help him. This guy is a certified Yamaha mechanic and will travel to you. Not sure if he'd come all the way to Gulf Breeze or not, but his card is below. Could be worth a call and see.

Let me know if I can help you out further.

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Thanks I'll store his info. I think I've got this one figured out. Fingers crossed I've been out a few times this week with no issue. But going to try an extended trip Sunday before I feel confident.

I believe it was just the rectifier. After testing all other parts of the charging system. I put the new one in on Tuesday and took it out then again on Wednesday but only for about an hour each time. I wanted to look for abnormalities and also trying to track down a leak.

Thanks for everyone's help

Good news @Alex Smith and fingers crossed.