1985 Evinrude 70 Tach not working

finish line 88

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Model E70TLCO. Tach was working with old motor but will not work since I changed to this newer motor. Tested the rectifier with my ohm meter and all checked to be working. I do have a wire coming off the motor cable assembly that has a knife disconnect terminal on it that is not hooked up to any thing. The color is either a light tan or gray. It is grouped with a yellow and black that goes into a plug by the rectifier.
I have another tach and tried that but that one does not work either.
Any help with this would be great. Thanks
 

Joe Reeves

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Re: 1985 Evinrude 70 Tach not working

If you checked the rectifier as follows and it checked out okay... then indeed it is okay. Was this your test procedure?

The "Gray" lead which should be attached to one of the yellow leads of the rectifier... or to a yellow/gray rectifier lead if it exists would be the wire that leads to the "Gray" wire of the tachometer... or to the "S" terminal of the tachometer if no wires lead from the tachometer. Check the continuity of that "Gray" wire with a ohm meter from the tachometer to the rectifier.

Does the tachometer needle bottom out to zero when the key is turned to the ON (RUN) position (engine NOT running)?

The majority of tachometers have four wires as follows:

Gray = Sensor. (connects to gray wire leading to rectifier)
Blue = Light bulb. (connects to 12v source of light switch... voltage present only when switch is ON)
Black = Battery ground. (DO NOT connect to "M" terminals of ignition switch)
Purple = 12v (connects to ignition switch "A" terminal

(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.
 

finish line 88

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Re: 1985 Evinrude 70 Tach not working

My yellow from the rectifier goes to the yellow on term. #1
Yellow/gray from rectifier goes to the gray and the yellow/gray from the harness. Jumpered term #2 & 3.
Red from rectifier to red. Jumpered term # 4 & 5.

I used your small rectifier test that I got from this forum.
The tach does not due anything. It is on zero. It is an OMC tach with just a single lead from it.
Thanks
 

finish line 88

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Re: 1985 Evinrude 70 Tach not working

I also checked continuity from rectifier to harness plug and from plug to tach and there is continuity
 

Joe Reeves

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Re: 1985 Evinrude 70 Tach not working

The tach does not due anything. It is on zero. It is an OMC tach with just a single lead from it.
Thanks

A tachometer with just one lead? Are you sure... just ONE lead? I don't recall ever seeing a tachometer with just one lead.

To have a tachometer operate on a 1985 70hp Evinrude, the tachometer must be one that operates off of the 6 pulse charging system (Dial on back sets to #6).

This old motor you speak of that the tachometer functioned okay on.... What was the year, make, and horsepower of that engine.
 

finish line 88

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Re: 1985 Evinrude 70 Tach not working

The tach is an OMC manufactured by Gale Products. I am incorrect about the "one" lead. There is a black ground lead and a gray wire to non regulated output side of alternator. There are no settings for pulse. The tach came off a 65 hp Johnson motor. The old motor was also a Evinrude 70 and I think is was a 1983 or 84 model # E70ELCNB. It had low compression.
 

Joe Reeves

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Re: 1985 Evinrude 70 Tach not working

The tach is an OMC manufactured by Gale Products. I am incorrect about the "one" lead. There is a black ground lead and a gray wire to non regulated output side of alternator. There are no settings for pulse. The tach came off a 65 hp Johnson motor. The old motor was also a Evinrude 70 and I think is was a 1983 or 84 model # E70ELCNB. It had low compression.

Normally the two (2) wire tachometers are for engine equipped with points/condensers etc... If the 65hp model you mentioned is the type with points/condenser, etc which I would think it is (you didn't state its year)... it will not function with your present 1985 70hp engine.
 

finish line 88

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Re: 1985 Evinrude 70 Tach not working

The 65 hp motors were late 70 something. I thought they were CDI and not point and condenser. I had used the boat for 3 years with the "old" engine and the tach worked fine. I was also CDI. I have 2 tachs and I swapped them out and so that is the reason I dont think it is the tach itself. Joe you have been a great help. If there is anything else I can check please let me know. Thanks
 

Joe Reeves

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Re: 1985 Evinrude 70 Tach not working

Sorry, I would need the model number to determine exactly what year/hp that previous engine was. Some were strictly points/condensers, others were electronic ignition but incorporates points, other yet were electronic ignition complete. As it stands, I don't know what else I could advise you with other than what I've already mentioned.

In your latest post.... you say "The 65hp motors were late 70 something'..... motors, plural, more than one?
 

finish line 88

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Re: 1985 Evinrude 70 Tach not working

Sorry I dont have the model number from the 65 hp motors. Yes it is plural. I parted out an old boat that had twin johnsons on it. The only info I can find on them is they were 1973. That is how I have two tachs. Model # on the "old" engine was E70ELCNB. Model # on "present" engine is E70TLCO. If the tach wont work on the "present" engine what would you recommend ? Make, model, etc ?
Thanks again
 

Joe Reeves

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Re: 1985 Evinrude 70 Tach not working

If those two (2) wire tachometers worked with the engine you mentioned 1982 70hp E70ELCNB, it should work with the present 1985 70hp engine E70TLCO. However if you intend to purchase a new tachometer, it would need to be....................

It would need to be a tachometer that functions off of the engine's 6 pulse charging system. It should be available at various marine stores and of course your local dealership.

It would normally have four (4) wires leading from it, colors of wires would be: Purple, Gray, Blue, Black.

There would be a dial on the back of it which you would set to number six (6).

If this tachometer does not work, there's something wrong with the engine's charging system or wiring.
 

finish line 88

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Re: 1985 Evinrude 70 Tach not working

Sorry for the late reply. Computer problems.
I am looking at a Teleflex Amega tach. I has a 6 pulse switch. To connect the tach the purple is 12 volt, the gray is the pulse, and the black is ground. What is the blue wire ?
Thanks
 

Joe Reeves

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Re: 1985 Evinrude 70 Tach not working

Blue wire is to power the light bulb within the tachometer for night time use. As per my previous reply.........

"Blue = Light bulb. (connects to 12v source of light switch... voltage present only when switch is ON)"

You don't read everything do you? :)
 
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