Newbie needs F40 Yamaha Tachometer help

bdaball

Recruit
Joined
Sep 25, 2014
Messages
3
Greetings,
This is my first post to this forum. I recently purchased a used 2007 Sweetwater Pontoon bost with a Yamaha F40 outboard engine. After going thru the initial dirty carbs and fuel issues the boat is now running sweet. One of the first things I did when I bought the boast last fall was to take it to a Yamaha dealer to winterize it and fix the tachometer. The tach was the only thing not working. Well, he sold me a new tach for a couple of hundred dollars and said your good to go. So, spring comes and I put the boat in the water and no tach, grrrrrrr........! I called the dealer back and he said "Oh, just bring it back, we'll look at it". Well the dealer is 40 miles away and that meant pulling the boat out of the water, (we leave it at our camp on a fresh water lake) paying launching fees and driving 80 miles. So I ran the boat all summer and again, it runs sweet. BUT no tachometer.

So, here we are this fall and I pull the boat out of the water. I found a dealer much closer to do the winterizing and asked him to check the tach. Now this dealer says, power is going to the tach but your rectifier/voltage regulator is bad to the tune of almost $300.00 for parts and labor.(????)


I'm okay with automotive principals and capable to do my own maintenance. I am totally new to outboards. Never had a boat before but after spending some time studying up, I'm sure I'll be winterizing my own from now on. I just wanted the satisfaction of a dealer doing it the first time in case I screwed it up.


So, can someone help me out with this tachometer issue. It is the OEM tach, I think Farreria is the name on the face. When you turn the key on the needle jumps up into the zero position. After that nothing. Everything else seems to be fine. Never had a dead battery all summer. Again, engine runs sweet. just no tach...???
 

boscoe99

Lieutenant Commander
Joined
Aug 22, 2013
Messages
1,815
Faria is a maker of tachometers. They don't make the Yamaha brand however.

The tachometer signal in your Yamaha does not come from the rectifier/regulator. If your battery voltage is approximately 12.6 volts before the motor starts and approximately 14.5 volts or so once the motor is running at a fast idle, a minute or so after the motor has been started, the rectifier/regulator is just fine.

The tachometer needs 12 volt power, a ground and a tachometer signal. The tachometer signal in you Yamaha comes up the ten pin main engine harness in a green wire. That wire connects to a small harness that runs to the gauges. That harness also provides the power (yellow wire) and ground (black wire) if the boat builder used Yamaha stuff. If not, all bets are off.

Here is what it looks like
 

bdaball

Recruit
Joined
Sep 25, 2014
Messages
3
So,... if the tachometer signal does not come from the rectifier/regulator then where does it come from? Seems it must be a generated signal from an electrical source within the engine, yes/no? Is it possible the rectifier could be handling the charge circuit but not the engine RPM's..? Boat is out of the water now and going in storage real soon. I have all winter to figure this thing out.
 

bdaball

Recruit
Joined
Sep 25, 2014
Messages
3
I know this is an old post but that little yamaha f40 is still running as sweet as before. Still no tach. Any thoughts?
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
I have a thought - In 5 years you haven't bought a Yamaha tach. Winter was a long one. :lol:
 
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