1985 90hp evinrude, possible reg/rectifier

[captain catfish]

i have a few problems and just want to make sure i'm spending my $$$ in the right place.
problem 1 - my brand new tach (1 didnt exist on the boat to start with) acts funny, works sometimes, doesnt work other times. i have double checked the wiring to the motor and every thing seems fine (no shorts, and good connections).
problem 2 - my battery only shows 12.6/12.7 with the boat running or not, (i will say we have been out and running for probably 3 hours or better and the battery has never been lower than 12.6.
i cant seem to find a test for the reg/rec. the stator is putting out 40+ ac volts. i can see no dripping of the stator coils (without removing the flywheel).

the boat seems to run great, just erratic tach function and i feel it should be charging (i have read) at least 14 volts to the battery.

can i test this $300 part before i spend that much?

 

[Joe Reeves]

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

 

[captain catfish]

so i can make sure i understand, i need to "run the boat" with the tach hooked to the yellow wire from the stator? i was afraid that would damage the tach, when i hooked the gray wire to the yellow (while on ear muffs) the tach does work, and reads the same as when hooked up normally ~1100rpm up to around 1500,.

this test confirms the reg/rectifier has failed? i thought i had read somewhere about some test that could be done on the regulator/rec... ?

i dont mean to be hard headed, sometimes im just slow on the take.

if you could clarify how this points to the regulator being bad.

thanks so much.

catfish

 

[Joe Reeves]

The engines that incorporate the voltage regulator/rectifier assembly have the tachometer signal lead (the gray wire) wired through that assembly, and when that combo setup malfunctions, it affects the tachometer. Now, normally, engines without the voltage regulator portion, those that just use a rectifier, the tachometer signal lead (the gray wire) is attached to the stator's yellow output lead.... the tachometer normally operates off of the engines charging system (the yellow lead).

So.... In my setup, all you're doing is wiring the tachometer as is was wired to the engines prior to the regulator/rectifier coming into existence. If the tachometer now functions as it should... the tachometer is obviously okay.

BUT, since the tachometer DOES NOT function properly when it is wired to the voltage regulator/rectifier assembly, then obviously that proves that the regulator/rectifier assembly is malfunctioning and will soon (I'll take any money wager you care to offer in differing with me) short out completely and turn what is under the hood into a melted mass of burnt wiring.

I assume this answers your question pertaining to clarification? :joyous:

 

[captain catfish]

that is a perfect explanation. thank you very much i am ordering the part. "melted mass of burnt wiring" is the last thing i need at this point in my limited boating experience.

thanks
guys like you that offer your experience and knowledge are such a tremendous help.

THANKS AGAIN
catfish

 

[Fed]

i thought i had read somewhere about some test that could be done on the regulator/rec... ?

That test involves putting a variable load device across the battery & an ammeter in series with the main positive to the battery.
Run the motor up on the water (4500 RPM), increase the variable load and see if the R/R puts out whatever the stator is designed for (6A,9A,35A). Then back the load off & see if the Voltage stabilizes at ~14.5 V.
The testing stuff could cost you as much as the new R/R.

If you want to keep it all original I'd test the stator resistances & if they're good then take a punt on a new R/R.
If you're not worried about keeping it original you could disconnect the R/R and fit a simple rectifier for peanuts even temporarily until you find a R/R laying in someone's shed for next to nothing.

 

[captain catfish]

thanks Fed, im going to replace the parts and hope for the best. i have lots of tools, and time, but not a lot of testing equip. like you said its just as cheap to replace some parts than buy 1 time use tools.