Outboard regulator/relay

[Rappey]

Mercury 50 efi. Voltage alarm went off. I have a gps speedo with voltage readout, it showed 17.5v. Slowed to displacement and voltage dropped to 12.3 which is the battery voltage according to my display.
I can adjust boat speed to change voltage output so concluded the voltage regulator has failed.
Bought a new ebay one for £25 compared to hundreds for genuine. Fitted it but voltage stayed at 12.3 at full throttle so that does not work. Bought another cheap one ,fitted it and that does exactly the same as the original failed one.
Is there anything else anyone can think of that could be causing this issue or are cheap ebay regulators useless?
Used genuine are still asking £80 which seems a bit much.

 

[William_H]

Sounds like there is no charging with the replacement regulator. Might indicate an incompatibility. Need a wiring diagram to track down what is wrong. Assuming the regulator system is similar to a car then regulator supplies a current top the field coil. (rotating part via brushes and slip rings)
However conceivably the alternator has permanent magnets and no actual charge control. That is done by series regulator which simply increase series resistance to reduce output voltage. Research needed (Vic may be able to help) ol'will

 

[VicS]

Sounds like there is no charging with the replacement regulator. Might indicate an incompatibility. Need a wiring diagram to track down what is wrong. Assuming the regulator system is similar to a car then regulator supplies a current top the field coil. (rotating part via brushes and slip rings)
However conceivably the alternator has permanent magnets and no actual charge control. That is done by series regulator which simply increase series resistance to reduce output voltage. Research needed (Vic may be able to help) ol'will

Not regulated like a car alternator.
It has magnets around the flywheel perimeter and coils under the flywheel.
The engine in question has a combined rectifier and regulator. There are at least two versions for different age models it is important, therefore, to quote the full engine particulars including the serial number when ordering.

The high voltage output from the original and one of the replacements, suggests that there may be no battery voltage on the sensing wire ( thin red wire) ........ check this .

£25 instead of more than £200 sounds too good to be true and may be just that!

 

[Rappey]

It's a very simple regulator, two yellows in, the ac input and a red and black out. According to what i read the regulator is suitable for all models of efi from 30 to 60hp.

 

[Alex_Blackwood]

It's a very simple regulator, two yellows in, the ac input and a red and black out. According to what i read the regulator is suitable for all models of efi from 30 to 60hp.

Sure you don't mean Rectifier as opposed to regulator? I would measure the ac voltage in and dc out see what you get. dc may be a tad different as you are rectifying peak ac voltage and measuring RMS. However they should be almost the same. Any full wave rectifier that meets the voltage and current parameters of your outfit should work OK. Fault may be on your ac side.
Edit:- Perhaps slightly different from a simple bridge rectifier? However all the ones I see are 5 wire? such as below.
https://www.motoelectrical.co.uk/pr...-UnAsEgm-uIbg-eFStrcgDQZ8Y_5ObrtMC7p84OZUK4yc

 

[VicS]

It's a very simple regulator, two yellows in, the ac input and a red and black out. According to what i read the regulator is suitable for all models of efi from 30 to 60hp.

Sure you don't mean Rectifier as opposed to regulator? I would measure the ac voltage in and dc out see what you get. dc may be a tad different as you are rectifying peak ac voltage and measuring RMS. However they should be almost the same. Any full wave rectifier that meets the voltage and current parameters of your outfit should work OK. Fault may be on your ac side.

It is a combined rectifier and regulator. With AC input it is obviously has to be a rectifier although some of the parts lists describe it as a rectifier/regulator while others just as a regulator.

With a simple unregulated bridge rectifier you will find the voltage output will rise to around 17 or 18 volts. This is generally Ok with low output stators fitted to small outboards but not for higher output stators fitted to larger outboards which have electric starting and possibly powered tilt and trim. The engine in question appears to have a 16 amp stator

There are definitely two different rectifier/regulators listed for a 50hp efi . They appear to have different connectors

CDI Electronics replacements illustrated

 

[Alex_Blackwood]

It is a combined rectifier and regulator. With AC input it is obviously has to be a rectifier although some of the parts lists describe it as a rectifier/regulator while others just as a regulator.

With a simple unregulated bridge rectifier you will find the voltage output will rise to around 17 or 18 volts. This is generally Ok with low output stators fitted to small outboards but not for higher output stators fitted to larger outboards which have electric starting and possibly powered tilt and trim. The engine in question appears to have a 16 amp stator

There are definitely two different rectifier/regulators listed for a 50hp efi . They appear to have different connectors

CDI Electronics replacements illustrated

View attachment 185930
View attachment 185931

The one I referred to has a check list for compatibility attached. Still unsure why OP said only four wire?

 

[Rappey]

Still unsure why OP said only four wire?

I said that to simplify things, but it didnt, sorry.
I said regulator rather than "regulator/rectifier" because its less typing and already stated what it is in title
The image you linked to is what i have. The grey wire is not used hence 4 wire. Suggestions have been that the grey wire is for tacho but others get tacho from elsewhere.There are also 6 wire versions. These sell for anything from £15 to £115 but look absolutely identical. Oem is £260. I would hate to buy one and find it does not fix the problem.
Interesting to read they may be two types, could that be a 5 or 6 wire, or two types of 5 wire?
I cant relate to any part number because there Isnt one on the old unit. The stator and rectifier part is working as im getting dc but the voltage just climbs with rpm increase up to 17.5v ,triggering the alarm. It beeps 4 times over a set timeframe which decodes as engine over voltage.
Good to learn the engine is 16 amp. No idea what power the engine consumes when running. Its a 4 cylinder, 1000cc, power tilt.

 

[Alex_Blackwood]

I said that to simplify things, but it didnt, sorry.
I said regulator rather than "regulator/rectifier" because its less typing and already stated what it is in title
The image you linked to is what i have. The grey wire is not used hence 4 wire. Suggestions have been that the grey wire is for tacho but others get tacho from elsewhere.There are also 6 wire versions. These sell for anything from £15 to £115 but look absolutely identical. Oem is £260. I would hate to buy one and find it does not fix the problem.
Interesting to read they may be two types, could that be a 5 or 6 wire, or two types of 5 wire?
I cant relate to any part number because there Isnt one on the old unit. The stator and rectifier part is working as im getting dc but the voltage just climbs with rpm increase up to 17.5v ,triggering the alarm. It beeps 4 times over a set timeframe which decodes as engine over voltage.
Good to learn the engine is 16 amp. No idea what power the engine consumes when running. Its a 4 cylinder, 1000cc, power tilt.

Being horribly pedantic , but you say Regulator/Relay in the title. No matter we have that bit all sorted.
If the one I referred to is what you have as original fit and you can use the "Check application and fit" table on their website, I would get that. As far as I can guess from what you have said it does look like a duff Regulator part of the unit. However even if the fault is elsewhere you won't know until you are certain you have a good regulator/rectifier.
If you could apply an ac voltage from a transformer, to the existing unit and somehow vary it you should be able to see if the regulator works and maintains a constant output. I know, easier said than done, so perhaps not practical. Just flying a kite