Tach pulse pick-up

[bonz_d]

Hi,

Trying to connect a tach to a 1978 35hp Evinrude and need to know where to pick up the pulse signal from on the engine.

I have an OMC control but the 3 prong connector had been cut inside and the control cable to the motor has a black plug with 5 wires and not the red plug. So I have no grey wire.

The tach is a Faria which shouldn't make a difference. Searched the forums and found no help for this.

Looking to get this tach in so I can properly size a prop for this boat and motor combination.

Thanks!

 

[bonz_d]

Re: Tach pulse pick-up

Anyone with any clues as to where else to try and find this answer?

 

[Silvertip]

Re: Tach pulse pick-up

Is your motor electric start? If so you can connect it to the input to the rectifier. If you don't have electric start there will likely be no rectifier and hence no stator and hence no signal for a tach. You would need a tiny tach or similar device that is triggered by a spark plug wire.

 

[bonz_d]

Re: Tach pulse pick-up

Thanks for the reply Silvertip!

Yes this is a 1978 35hp 35852R with electric start. Doesnt even have a recoil on it.

I see on the BRP site the rectifier is shown as part #6 but can not seem to locate it on the motor. I can locate the power pack and a terminal block.
I also see a grey-black wire coming from the stator.

So where is the rectifier normally mounted? How do I determine the imput wire to the rectifier?

I really need to invest in a manual for this thing. Been watching ebay but haven't come across one yet as I plan on keeping this for a long time.

 

[Silvertip]

Re: Tach pulse pick-up

Few people these days know that there is a public library in their town. You would be surprised at the selection of manuals they have. And the best part -- you can look at them for free. The rectifier will have two wires going into it (normally yellow) and one coming out (normally red). The input leads will come out from under the flywheel go to a terminal block and from there to the rectifier.

 

[bonz_d]

Re: Tach pulse pick-up

Just happens that we have one of those in our town and I even happen to be card carring. Happens they also have access to a large metro group but guess what! They don't have that manual. Already checked and believe it or not we are located on Lake Michigan. But thanks for that lead.

Now if we both can put the sarcasm aside I really do appreciate the help. Been trying to find out how to hook this up all spring and all the spare cash has been going into refitting the boat and trailer.

I will go look for the wires you mention and post back

Again, Thanks!

 

[bonz_d]

Re: Tach pulse pick-up

Thank you!

That was easy once I knew what I was looking for. In this case and for any others that might need to know this rectifier is located right under the terminal block.

This rectifier has 2 yellow/blue stripe, 1 yellow and the red wire. Guess now all I need to do is determine which of the yellows to use.

Hopefully now I can get an RPM reading to help size a new prop.

 

[Barnacle_Bill]

Re: Tach pulse pick-up

Either yellow wire coming from the stator will work. Note tho that if your rectifier is bad your tach most likely will not work.

 

[bonz_d]

Re: Tach pulse pick-up

Thanks for the reply and tip. Can't wait until tomorrow to test it out. Unfortunately I have to work tonight, so I will post back tomorrow the results.

 

[bonz_d]

Re: Tach pulse pick-up

Sorry for the delay in getting back with te results. Rotten work schedule.

The tach is in and now functional with the help you both have provided. Thank you both very much! Now I just need to get it on the water and see what it's turning with the currant prop.

Thanks, Kevin

 

[Silvertip]

Re: Tach pulse pick-up

Glad you got it figured out. I and most others on the forum are not intimate with every engine produced by every manufacturer on the planet so some things just need to be researched until the solution is found or you get lucky and someone with the same exact engine or a tech that is familiar with that exact engine comes along. Manuals are worth their weight and contrary to popular belief, one does not always need the "exact" manual. If you didn't know what a rectifier looked like, a simple "google/yahoo" search (Evinrude Rectifier) turned up this one in about 15 seconds. You then look to see if you can find one like it on your engine. Manuals (exact or not) can provide the same information.

http://www.boatbandit.com/johnsonevinrude-rectifier-7164.aspx

Rectifiers come in many shapes and sizes but the most common was about the diameter of a quarter, mounted in a metal enclosure and has three or four wires on it. It took about 15 seconds to find this one.

 

[bonz_d]

Re: Tach pulse pick-up

Thanks, and you are correct. I guess I was just thinking that these engines are so common that someone would know where to look. After bhile posted I did a search for "checking rectifiers" here in the forum and found much more than I did by searching tachs. Guess I became too focused in my search or didn't think of trying another avenue. But I learned alot during this exercise. Not just about the tach but also about the entire electrical system. Also learned that 1976 was the end of the point ignition as they were and in 1977 they started using stators in the electric start models. So in my case it looks like any manual from 1977 up should cover most basic things in this model run.

Anyways, thanks again and let's go boating!

 

[mark alford]

Re: Tach pulse pick-up

would this be the same as a 1986 nissan 70hp? to hook up the tach?
Mark