Over voltage and rpm loss -related?

Smithyyy · 01 July 2013, 06:45

Hi
My Mariner 50 2-stroke ( mid 90's age) just started showing 2 symptoms - the voltage generated is high (15-16V), and the engine suddenly drops revs at WOT, from around 5,100 to 4,300 or so. Both problems seem to be intermittent. The high voltage says regulator going bad to me, but it seems strange that the two things have happened at the same time. Bad earth would be another guess at something that might cause more than one problem - but would that make the voltage read HIGH, or cause rev loss? Any thoughts please on this or other possible causes? Thanks!

biffer · 01 July 2013, 07:27

Buggered battery leads, does the motor sometimes turn over a little slow on first startup

Nos4r2 · 01 July 2013, 10:25

Quote:

Originally Posted by biffer

Buggered battery leads, does the motor sometimes turn over a little slow on first startup

I'd go with that (more likely) or the regulator.

It's possible the revcounter is dropping out when it can't cope with the overvoltage.

9D280 · 01 July 2013, 15:36

How "mid 90s" are we talking here?

The Clamshell type only had a rectifier.......

(Mine now has a Reg/Rect unit off a Honda!)

Smithyyy · 01 July 2013, 22:06

Thanks for all the suggestions, much appreciated. To answer the points raised:
- sounds like a good look at the engine leads (+ve AND -ve I assume) and isolator switches is in order before splashing out on a regulator
- good thought to question the rev counter but the rev drop is real, you can hear it and feel it
- the motor is 1993 from looking up the serial number but not I believe a "clamshell" (which are I think the ones whose cowl splits along its length?). Don't know the nomenclature for mine but it looks like the one in the attachment. It has the "red stator" and control box which I believe are retrofits for the original "black" stator, then a 5 wire (2 red, 2 yellow, 1 grey) regulator, part number 815279-3

Interestingly the new regulators I can find with the same part number are all 6 wire (with an extra black ground wire) presumably if I do end up getting a new one I just attach this to a ground point and it replaces the old 5 wire model?

Cheers

Festinghouse · 01 July 2013, 22:19

yes, just ground the black. before spending money google search the tests to carry out on both the stator and rectifier using a multimeter - these are very simple tests and should help pinpoint the problem.

9D280 · 02 July 2013, 08:50

.....and that definetly isn't a clamshell!

biffer · 02 July 2013, 09:14

Buggered battery leads

Smithyyy · 02 July 2013, 23:48

OK thanks again. Yes Biffer I'll check the battery leads! :-)

Smithyyy · 03 July 2013, 07:21

OK, so last night I tried to check the charging circuit as per the manual. This says to disconnect the red wires from the starter solenoid post and connect the "thinner one" to a 9V battery (negative of which goes to engine ground), and the "thicker" red wire to an ammeter the other end of which goes back to the solenoid post. So presumably "thick" is the output, "thin" is the sensor and the 9V battery simulates a boat battery that needs charge

But my two red wires are the same diameter :-( One is a single wire all the way, the other has connections in it, including to the engine 20A fuse. I'm assuming the former is the sensor, the latter is the output, but anyone know please? Just nervous of frying something if I connect things the wrong way round...

Thanks