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Author Topic:   Mercury Voltage Regulator Kit Installation
ScottS posted 09-23-2009 09:44 PM ET (US)   Profile for ScottS   Send Email to ScottS  
My motor is a 2004 [Mercury] 60-HP EFI Bigfoot. I ordered a Mercury voltage regulator using an updated part number provided by Mercury Parts Express. When it arrived I was surprised it was a kit and not just the regulator. The kit also includes an exhaust cover, thermostat, fuse assembly, gaskets, and other items. Do I need to replace all these parts? Or, can I just replace the regulator and save the other parts for future maintenance? I can't find a fuse on the motor, so this would appear to add one. Any idea why it contains a new exhaust cover or thermostat?

The voltage regulator kit is part #893640A02. FYI, my motor was not part of the regulator recall.


jimh posted 09-23-2009 09:48 PM ET (US)     Profile for jimh  Send Email to jimh     
Did the replacement part kit include installation instructions?
ScottS posted 09-23-2009 10:06 PM ET (US)     Profile for ScottS  Send Email to ScottS     

Yes. The instructions show how to replace all the parts, but there is no explanation why. The instructions are for a 40/50/60 four stroke. I wonder if the added fuse and other replacement parts were to solve the regulator problems on the 2002-2003 model years?


jimh posted 09-23-2009 11:11 PM ET (US)     Profile for jimh  Send Email to jimh     
I haven't researched this, but I suspect the replacement kit contains a fuse in order to prevent a fire hazard or melt down. I recall some prior discussion about electrical problems where the regulator got too hot, melted, and even started a fire. The addition of a fuse may be intended to avoid that sort of problem.

As for all the other parts, they may be related to the problem I refer to above, too much heat. Perhaps they are more heat resistant parts. You might call the Mercury repair or customer service hot line and ask about this topic. If you discover something, let us know. I am just speculating, based on a vague recollection of prior discussions.

bloller posted 09-24-2009 10:51 PM ET (US)     Profile for bloller  Send Email to bloller     
Your motor was not part of the voltage regulator recall yet you are replacing it after only 5 years. I hope mine lasts longer on my 2004 Mercury Fourstroke.
ScottS posted 04-11-2010 09:17 PM ET (US)     Profile for ScottS  Send Email to ScottS     
Here's a follow up on my regulator replacement.

I replaced my regulator because my tachometer was erratic. Several posts on this site pointed toward the regulator being the problem. The dealer had already replaced the tach under warranty, which didn't solve the problem, but neither did the regulator replacement. I later determined the tach problem is due to the ground wire going from the motor control to the tach. The ground wire appears fine when I do a continuity check, but if I run a second ground wire directly from the battery, then the tach works 100% of the time.

As far as the regulator replacement, it took several hours, but was simple to do. Besides adding a new fuse, everything looked the same as the parts my motor already had. I went ahead and installed all the parts from the kit. It was a simple bolt on and plug in process and the instructions were good. The hardest part was scraping the old gasket off the motor, which took over an hour. The only mistake I made was when I installed the temperature sensor. I added Teflon tape and tightened it too much, so I broke it and had to buy a new one. Don't add Teflon tape and just hand tighten it. Also, the instructions say to remove the bottom cowls, but I found I didn't need to.

I paid $143.08 for the regulator kit from My temperature sensor mistake cost me $26.32 from Doing the repair myself seemed better than having my boat sit at the dealer for several weeks. It didn't fix my tach, but was a good learning experience and the new parts can't hurt.


jimh posted 04-11-2010 10:03 PM ET (US)     Profile for jimh  Send Email to jimh     
Scott--Many thanks for the follow-up article on your repairs.
morganranch posted 07-29-2010 12:13 PM ET (US)     Profile for morganranch  Send Email to morganranch     
Thanx Scott for the tips on replacing this stuff. I did it yesterday on my 2004 50hp merc. In my case the voltage regulator actually burnt up and left us stranded on our lake. The replacement took me 6 hours, 2 of which was getting the old gasket off. I did have to remove the lower cowls as I could not accsess all the exhaust cover bolts otherwise. The first symptom on mine was erratic tach readings, then a couple weeks later the batteries were not charging from the moter. Then an hour or so after that alarms went off, the engine went into "limp" mode and there was smoke pouring out of the moter. Turned out there was no actual flames just a lot of smoldering. Shuting the engine off quickly was the key, with no electricity the regulator cooled down and quit smoldering. And for added fun, my mother in law was onboard for the first time ever (afraid of boats and water) she was sure we were sinking. That was the first and last time she'll ever go boating with us, so at least some good came of it.
bloller posted 07-30-2010 10:42 PM ET (US)     Profile for bloller  Send Email to bloller     
I had to replace the regulator recently on my 2004 60HP Mercury Fourstroke at only 105 hours. It was not part of the recall. I was able to identify the problem right away as I have Smartcraft guages and noticed low voltage. Regulator was slightly burnt but did not yet smoke or cause the motor to go into "limp" mode. I did not install the new exhaust cover only the regulator and fuse assembly. I have put about 30 hours on it since with no problems. Mercury certainly dropped the ball on this one.
morganranch posted 08-03-2010 11:15 AM ET (US)     Profile for morganranch  Send Email to morganranch     
Update, this replacement did not solve my erratic tach problem either. There is a calibration screw on the back of the tach. I turned it left and right then put it back where it was originally and that did it! Must have got some corrosion in there or something. I love an easy fix. Got lucky on that one.
L H G posted 08-03-2010 08:06 PM ET (US)     Profile for L H G    
With a Mercury, an erratic tach signal is either the tach itself, the selector switch on the tach, or the engine rectifier. I'd bet on the latter.
LIC412 posted 09-02-2010 09:24 PM ET (US)     Profile for LIC412  Send Email to LIC412     
I am just joining in on this discussion. I replaced the voltage regulator on 2005 Mercury 60 HP Bigfoot. I got the kit, but just replaced the regulator and not everything else. Six weeks lateer, the regulator failed again. Not sure what the problem is, but it does not give me much faith in Mercury.
bloller posted 09-02-2010 09:59 PM ET (US)     Profile for bloller  Send Email to bloller     
I have now put about 45 hours(4 months) on my motor since installing the new regulator and all is well. How many hours did you put on the motor in those six weeks? Please keep us informed on where you go from here as I fear I may be in the same boat as you.
Nauti Tauk posted 09-03-2010 06:19 PM ET (US)     Profile for Nauti Tauk  Send Email to Nauti Tauk     
The voltage regulator on my 2003 90hp4s burned up and was replaced along with some other ancillary hardware. The new unit was quite a bit larger physically than the regulator it replaced. The replacement was over two years ago and no regulator problems have arisen since. Hour wise....? no guess, but a bunch.

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