Hi
The engine is running fine but on giving it the once over , as i have only recently brought the thing and got it running..
I noticed this wire problem from the manual i think the box is a rectifier ?? as the yellow wire in the manual shows going to a rectifier ..
Well the previous owner has obviously had a short and fixed it by adding a new orange wire , and just left the 2 wires in there corroded and burnt state.
I have taped the burnt out end with red insulating tape , which you can see on pics.
Now is the rectifier or whatever you guys say the burnt out bit is ? Ok to just tape up and carry on as the engine is still running ok ..
Or should i get new and wire the 2 burnt out wires in again as it should be , BUT !! the question then is what caused it ? The ignition switch is not the original so maybe thats why they have now been left off ?
anyways heres the pics . views and suggestions appreciated
Now looking at the burnt out box .. North position is the new orange wire , South position has the yellow wire , and the 2 burnt out wires one is yellow and the other is like a grey or an off white colour both was on peg at WEST position which is now melted away as per pic.
Advice needed , its running still so i assume its been like this a fair while ?
I have taped the 2 wires in red insulating tape , so you can see what and where they are ..
yes, that is your rectifier and YES it needs to be replaced and wired correctly.
The two yellow wires go to your stator, grey runs back to your main wiring harness and the red goes to your starter solenoid where it connects to the positive lead from your battery.
The purpose of this piece is to regulate the AC voltage from your stator into DC to charge your battery.
Can not see any red lines on the yellow just yellow...
What year is your motor? Look on the bracket where the engine mounts on the boat and post the serial #. I'll need that to be sure of the wiring but what I've posted above has been the case on all late 70's early 80's merc I've seen.
Quote:
Originally Posted by big pete
What also worries me is why it burnt out in the first place
Probably a bad ground somewhere that may or may not have been corrected. Start at the battery and clean, examine, and test all connections. Also check the connections in your control box at your ignition.
Anything corroded, rusted or frayed needs to be repaired or replaced.
I Got one its the newer type apparently looks a lot thicker and chunkier than the one on at the moment .. So maybe they had a ongoing problem with them being weak and melting ..
So i am going to have to modify the mount to get it to screw on , but sure i can handle that . and then wire it up and see what happens ..
The cost was a £ 50 , thats about 75 US dollars i think in your money , expensive isnt it ?
ps; I got it from my local Boat place at Porto Cristo marina , reckons he keeps regular wear parts in stock , so thats good news for me
Last edited by Big Pete : November 2nd, 2009 at 02:30 PM.
Reason: ps added
yes, that is your rectifier and YES it needs to be replaced and wired correctly.
The two yellow wires go to your stator, grey runs back to your main wiring harness and the red goes to your starter solenoid where it connects to the positive lead from your battery.
The purpose of this piece is to regulate the AC voltage from your stator into DC to charge your battery.
Oh yea , also thanks for this useful info your like my local mechanic it is appreciated ..
Replaced the Rectifier with the new one ; heres the old one . Reduced: 69% of original size [ 922 x 612 ] - Click to view full image
Safe to assume its pretty well broken ..
So in goes the new one , but wires burnt quite badly requiring expertise to get things serviceable again ..
Hence as per pic, i added a new wire which i had to double up to get the result..
Reduced: 69% of original size [ 922 x 612 ] - Click to view full image
Now after getting the thing on and rewiring the stuff i had to remove to get to the Rectifier , its all ready for testing ..
So i start it up and check with the Meter , can only use the idle increase so it runs on tickover first and then i add the increase.
On the Battery i get 12v and nothing seemed to alter on tickover , with a slight increase on revs it still seems much the same and with the meter its hard to see much of a change..so i then closed the seat .
I check the dashboard voltmeter this sits at 11v before start up , 12 v on tickover but when i add a few revs it goes way up to 14.5v
Now is that ok seemed pretty high to me ? And as with the boat on mufflers i shouldnt rev it any more as you can get runaway .. This is due to no load on the propellor which sends the engine berserk apparently ..
Here is the Video link for the test .. have a watch at the Voltmeter..
After sitting down having my well earned cup of tea from all the wiring work..
I wondered if the engine had maybe a Regulator and that was indeed blown ? So i drag the manual out and as you will see NOPE no regulator in the wiring loop..
Reduced: 97% of original size [ 656 x 436 ] - Click to view full image
Sorry for making you twist your head , should of rotated it i know
Anyway just by pure luck i spotted something !!!!
The rectifier has 3 posts 1 is marked + and the other 2 are blank ..
The rectifier wiring on the burnt out one is as this. assuming the + is at North position .
North (+) = Red Wire
West = Yellow with the Grey
East = Yellow
Now what i did was copy the same assuming thats how it should be , logical right ?
BUT !!! Look at the wiring diagram very closely ?
as below;
Remember !!
Red + is the North position
So looking at the diagram close it actually shows .
West = Yellow
East = Yellow and Grey
So Could this be the reason the other one Burnt out maybe?? Or does it not make any difference ??
My own feeling is i am inclined to rewire as per the diagram , just because the manual says so even though there is NO marking on pegs at East and West on the Rectifier .
I used my trusty Meter on the pegs when the thing was new and NOT fitted and i got as ;
North + to East post ,, contact made ie complete circuit
North + to West post ,, NO contact made ie NO complete circuit ..
I check the dashboard voltmeter this sits at 11v before start up , 12 v on tickover but when i add a few revs it goes way up to 14.5v
Now is that ok seemed pretty high to me ? And as with the boat on mufflers i shouldnt rev it any more as you can get runaway .. This is due to no load on the propellor which sends the engine berserk apparently ..
14.5v is normal and is what you want to see when charging. A fully charged battery should have a standing charge of 12.6v to 12.8v. While charging it may go up as high as 15v or more.
Make sure you are using a good marine battery and you are all set
So looking at the diagram close it actually shows .
West = Yellow
East = Yellow and Grey
So Could this be the reason the other one Burnt out maybe?? Or does it not make any difference ??
My own feeling is i am inclined to rewire as per the diagram , just because the manual says so even though there is NO marking on pegs at East and West on the Rectifier .
I used my trusty Meter on the pegs when the thing was new and NOT fitted and i got as ;
North + to East post ,, contact made ie complete circuit
North + to West post ,, NO contact made ie NO complete circuit ..
So what you reckon ???
You've got it right the first time. Positive + on the rectifier goes to the Red wire on your wiring harness. The other two go to the stator (yellow) and the grey goes on the lower of the two stator terminals.
Advice on Mercury 80 3 cyl 2 stroke electrics
and is it likely to do the same again when i am out in the ocean 
your like my local mechanic 
Reduced: 69% of original size [ 922 x 612 ] - Click to view full image
from all the wiring work.. 
Linear Mode
