94 Mercury Pro Max voltage regulators

[Warrenroadie]

Good afternoon,

Both of my voltage regulators appear to have discolored and/or burned areas on the clear covering facing outward. Have only run boat once since I purchased so I have not seen any issues thus far. How do I check the functionality of these regulators. Basically how do I determine they controlling voltage properly. Thanks for your help!

[WillySteve]

Voltmeter, one lead to the positive red terminal/wire the other to ground with the engine running at 2-3000rpm. Anything less than 13v is not charging.

[XstreamVking]

I believe the clear ones were always suspect. They can fry the stator too. I would replace them with newer black ones. I have had my share of trouble with the clear regs on several motors of that vintage. Also check the batt connections, if loose they will fry the regs quick.

[Dave Strong]

There is a service bulletin on these regulators, had issues with mine overcharging over 16 volts. The updated part number is 883071A 1. I know for a fact Fullers Marine a.supporting vendor here stocks them.
I tried replacing just on with a sierra unit and it still over charged, after replacing both with the updated ones all is fine.

Dave

[Warrenroadie]

WillySteve as far as checking regulators, I have two red wires from regulators, which one or either?
Dave Strong, I am getting 14.2 volts back to starting battery. Both of these regulators just look physically bad compared to motor. Could this have anything to do with my tachometer not working?
How to do find "Sponsors" website on this site?

[FORBESAUTO]

Tach signal comes from regulator. So your probably right at least one is bad. Tach wire is grey one, only one will be using, can swap grey wire from one to other to check. I would change both as suggested

[Dave Strong]

WillySteve as far as checking regulators, I have two red wires from regulators, which one or either?
Dave Strong, I am getting 14.2 volts back to starting battery. Both of these regulators just look physically bad compared to motor. Could this have anything to do with my tachometer not working?
How to do find "Sponsors" website on this site?

If you see 14.2 at the battery then I would say its charging, as was said swap the grey wire to the other regulator and see if the tach works. If not try a known good tach before you rush off and buy regulators. Fullers Marine phone number is 732-736-0444.


Dave

[Warrenroadie]

Thanks for troubleshooting info will check tachometer on other regulator too. Thanks for Fuller's contact info.

[Warrenroadie]

One more question while I have your attention. Why do these outboards have two regulators? Is it because they are race outboards?
Thanks!

[Dave Strong]

One more question while I have your attention. Why do these outboards have two regulators? Is it because they are race outboards?
Thanks!

40 amp system uses 2 regulators.

Dave

[Warrenroadie]

Thanks Dave!

[WillySteve]

Yes, either red wire is fine. Looks like both are working, at least when you checked it.
The grey Tach hookup wire can quit working on a regulator so do as Dave said but, IF....changing the grey wire to the other regulator doesn't get your Tach going then on the rear of the Tach you'll find a small dial, which is set on a number. Note the number and take a small screwdriver and twist the dial back and forth a dozen times or so, then set it back to where it was originally!
Sometimes the small contacts inside will corrode from moisture and this will help to clean them.
A Tach with dirty contacts usually jumps around while running however it can just stop working!!!
Good Luck!

[Dave Strong]

BTW the regulators the bulletin says to use only have one red wire so you must cap the second wire. The existing one comes with a fuse holder and a 20 amp fuse. For V6's you need to replace it with a 30. Should be instructions in the regulator.

Dave

[Warrenroadie]

Thanks, I'll do this tonight. It currently goes to 600-700 rpm's when engine off, turn the ignition key on and it goes to zero. If I remember correctly it was on 6 which was for 8 cylinder and I rotated it to 4 Which was for. 6 cylinder. It had no change at that time. I will rotate it around some more. It is the original 0-10000 rpm tachometer.