I have a SeaDoo X-20 with the 2002 Mercury 240 EFI M2 Jet Drive motor. I replaced the battery. I installed an aftermarket voltmeter in the dash to monitor the battery status. At cold start up, the voltmeter reads ~14v, however after a few minutes the voltmeter drops and the engine runs off the battery, without any recharging of the battery, therefore running the battery down. I've taken a look at the electrical diagrams and am wondering what would cause this. Is it the voltage regulator or the stator assembly? Does anyone know what could be causing this?
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Battery not being charged during engine operation
- Thread starter bmiller
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So a mechanic is looking at the engine further, but he has already mentioned that he would recommend replacing the stator first because he says if they replace both voltage regulators and the stator is the bad, it could fry the new voltage regulators. Is it possible for the stator to do this? Is there a way to test the voltage regulators to determine if one (or both) are bad before replacing the stator which gets quite expensive?
Dr Honda
Well-Known Member
A stator can be checked pretty easy. There is a spec for the resistance of each coil/leg of the stator. You check that... and you check to see if there is a short to ground. And finally... you give it a visual inspection. The wire on it has an enamel coating. If they short out, or have problems... the coating will cook, and turn dark or even black.
I don't work on Merc engines every day... but it's WAY more common for the regulator/rectifier to burn up.
If your mechanic can't give you an answer on if the stator is good or bad... I wouldn't be letting him work on it.
I don't work on Merc engines every day... but it's WAY more common for the regulator/rectifier to burn up.
If your mechanic can't give you an answer on if the stator is good or bad... I wouldn't be letting him work on it.
Dr Honda
Well-Known Member
Since I get pissed at mechaics... because most of them are idiots. (I said most... not all) I just pulled the manual for the 240 Merc, and decided to help you out. It's got a goofy system. It resembles a dirt bike system. (with 6 spark plugs)
Your stator has a high speed, and low speed (High voltage) cap charging system for the ignition, and a non-phasing (un-balanced) AC charging system. Chances are, if your stator went bad, it would not be running properly.
OK... the resistance between the YELLOW wires should be 0.25 to 0.45 Ohms. There should not be continuity to any of the other wires, or to ground.
If that checks out... there is no reason to replace the stator. (and to pay for the labor to remove the flywheel) The "PAY FOR THE LABOR" thing is probably why the mechanic wants to change it first. He can only charge you 15 minuets labor to change the regulator, but he can charge you 2 hours to change the stator.
Sorry... still pissed off.
OK, so, if that checks... you are fine and the regulator is the problem.
Oh... one last thing... if you have a shorted regulator... it could cook the windings in the stator in just a minute or two. There is almost no way a bad stator can kill a regulator in an unbalanced system. (becasue it just won't have an output)
Finally... with that said... in a true 3-phase system, the rectifier sometimes has to stay balanced to run cool. But you don't have a 3 phase, so tell the mechanic you want to boat back. Change it your self (5 wires, and 2 screws) and save yourself an ass load of $$$$.
If you have any more issues... let us know. :cheers:
Your stator has a high speed, and low speed (High voltage) cap charging system for the ignition, and a non-phasing (un-balanced) AC charging system. Chances are, if your stator went bad, it would not be running properly.
OK... the resistance between the YELLOW wires should be 0.25 to 0.45 Ohms. There should not be continuity to any of the other wires, or to ground.
If that checks out... there is no reason to replace the stator. (and to pay for the labor to remove the flywheel) The "PAY FOR THE LABOR" thing is probably why the mechanic wants to change it first. He can only charge you 15 minuets labor to change the regulator, but he can charge you 2 hours to change the stator.
Sorry... still pissed off.
OK, so, if that checks... you are fine and the regulator is the problem.
Oh... one last thing... if you have a shorted regulator... it could cook the windings in the stator in just a minute or two. There is almost no way a bad stator can kill a regulator in an unbalanced system. (becasue it just won't have an output)
Finally... with that said... in a true 3-phase system, the rectifier sometimes has to stay balanced to run cool. But you don't have a 3 phase, so tell the mechanic you want to boat back. Change it your self (5 wires, and 2 screws) and save yourself an ass load of $$$$.
If you have any more issues... let us know. :cheers:
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WAJetboating
Member
Correction: The manual is misleading in this area. What you're describing is the system for the 210 carbed version of the 2.5L engine. He has the 240EFI. They're both covered in the same manual, and the manual is very confusing in its coverage of the stator and ignition system. But trust me, the 240EFI does not have the separate high speed/low speed setup.
Hope this helps....
WAJetboating
Member
Whoa, hold on a minute!
First of all, you say you have the 2002 version of the engine. Are you sure about that? The 2001 and below have the two standalone regulators. Starting with 2002, the engine went to a belt-driven alternator that integrates the rectifier and regulator within the alternator.
If you do have a 2001 or 2000 version with the external regulators, there's a factory recall on the regulators for some 240EFI engines. Grab your engine serial number and call Mercury at 920-929-5040. They will tell you if the recall applies to your engine, and if your engine has received the new regulators yet. If not, a local dealer can obtain the regulators for you at no cost. They will install them for you (at no cost), or you can install them yourself if you return the old ones to be shipped back to the factory (which is what I did).
Don't spend a penny until you make the phone call. You could get your new regulators for free.
Also, if you do end up replacing the regulators, get some heat sink compound (from any reputable computer shop) and use a thin layer between the metal backs of the regulators and the metal mounting plate to which they attach. The metal bracket is meant to act as a heat sink and the compound will reduce the thermal impedance at that interface, helping to keep the regulators cool.
Report back!
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WAJetboating
Member
As a side note: On my 787 Rotax engines I can disconnect the rectifier/regulator module and the engine will run solely on the battery. I usually have to do this at least once a year, since those rectifier modules seem to die on me about that often. I've replaced quite a few.
But on my 240EFI engine, disconnecting the regulator outputs prevents the engine from running at all. It won't even start. So I wouldn't automatically presume that the regulator(s) are bad if the engine will start and run. Perhaps their output voltage is LOW, permitting the engine to start but having insufficient voltage to charge the battery... not really sure.
Do you have a multimeter? If so, between me and Dr. Honda we should be able to walk you through the tests necessary to do your own diagnostics. They're not difficult and everything is accessible without odd tools.
Start by calling the factory to see if the recall applies to your engine. Let us know their answer, and whether you have a multimeter, and we'll try to help.
I checked and the recall doesn't apply to my engine.
I do have a multimeter. If you can point me in the right direction, I am listening...
Another thing that was happening a few months ago was the tachometer was acting up. At low speeds and gradually accelerations, it worked fine. However when I throttled hard, it immediately dropped to zero and then spun back to the correct RPM. I'm guessing this could be related to my problem.
I do have a multimeter. If you can point me in the right direction, I am listening...
Another thing that was happening a few months ago was the tachometer was acting up. At low speeds and gradually accelerations, it worked fine. However when I throttled hard, it immediately dropped to zero and then spun back to the correct RPM. I'm guessing this could be related to my problem.
WAJetboating
Member
So do you have the separate regulators (2001-), or an alternator (2002+)? The test procedures change depending upon which version you have.
I purchased 2 aftermarket voltage regulators for $65 each. I replaced the top regulator and started it up. No real change on the voltmeter. I then replaced the lower regulator and started it up. Voltmeter finally read "charging". Took the boat out on the water yesterday and ran it for about 4 hours. Ran perfectly! Big thanks to Dr Honda and WAJetboating for steering me away from the stator replacement. Probably saved me $750. :hurray:
Thats good to hear. Great resource we have here.
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