Merc 1150 tachometer installation

[gregtobin]

Sorry if this is a partial duplicate posting, my computer just wacked out.

I wired up my new tachometer last night and want to check my RPMs tomorrow. Most of the wiring on my 1977 Glassmaster with 1974 Merc 1150 have been replaced and are no longer the correct color code.

The brown tach wire that plugs into the controller box did not work so I was looking for a pulse from the motor. I think I found one in the top connection in the top connector block in the motor. This connector has what looks like an original Green wire (marked G in the picture, if I can load it). I had been looking for the rectifier but couldn't identify it (is it the unit with a question mark over it?). The tach seems to work OK, but I want to make sure that it is accurate. Will the connector I used give it the correct reading?

And, the brown wire that enters the engine from the big plug has been spliced with a blue wire that goes to the connector just below the Green wire that I used. What does this connector do? Is it the correct site to monitor battery Amps? The reason I ask is that the brown tach wire was connected to the Ammeter in the instrument panel.

Thanks!
Greg

 

[gregtobin]

Re: Merc 1150 tachometer installation

I can't see the details in the picture that I uploaded. Looking at the upper connector block, the top wire is Green and the next one down is Blue. I connected the Tach to the green wire post and the non-working amp meter is connected to the blue wire post.

BTW, I've seen many posts with very nice large pictures in the text, not as thumbnails. How do you get around the 100kb size limit?

 

[erniex]

Re: Merc 1150 tachometer installation

Greg,
Check out this post from the other day, http://forums.iboats.com/showthread.php?t=212132
Good explanation on tach connections. Typical aftermarket tach would receive its signal from one of the A/C wires from the rectifier. Find the yellow wires coming out from under the flywheel and follow them down to the rectifier. Two yellow wires into the rectifier and one red wire out. Original mercury tachs ran off the switchbox, however any outboard tach will work when connected to one of the A/C rectifier terminals.

Hope this helps

Ernie

 

[gregtobin]

Re: Merc 1150 tachometer installation

Hi Ernie-
Most of the wires have been replaced and the color codes were not retained. I had been looking for yellow rectifier wires, but can't seem to find them.
My three repair manuals are also not very good at identifying components. Where do you suppose the rectifier is located and how best to identify it?

Regarding the previous thread, the brown wire that goes into the big plug-in connector (the one that exits the motor and goes into the boat) has been cut and replaced with a blue wire that might be visible in my photo. This blue wire (which is essentially the brown wire) goes into the upper connector box, second connection from the top. This brown wire now runs to the ammeter (which doesn't work).

Thanks
Greg

 

[Chris1956]

Re: Merc 1150 tachometer installation

Greg, The tach signal can be gotton off either of the two stator wires. The stator wires may be found in that two-wire terminal block 1/2 way up the engine block, where the wires from the stator (under flywheel) join the motor harness. In 1974, Merc may have used the switchbox to provide the tach signal to a proprietary Quicksilver tach. They gave up on that idea by '77, when all tachs were standardized.

BTW - Your rectifier is likely the thing with the ? mark. It was a big ugly red device with three connections, in 1974. it became a 1"X"1 X3/8" "cube" by 1977.

ABTW - it appears you have two switchboxes. That is strange since my 1973 and 1977 inline engines each had the same single switchbox. Maybe the bottom rectangular device is a starter solenoid??

 

[Chris1956]

Re: Merc 1150 tachometer installation

Correction, Your ugly red rectifier is likely buried in the bottom coil. On second glance the ugly red device near the ? mark is your coil.

 

[ricksrster]

Re: Merc 1150 tachometer installation

sorry. I had the wrong diagram.

 

[AMD Rules]

Re: Merc 1150 tachometer installation

Upper box with 4 connections is the switchbox.

Box just below that with 3 connections is the rectifier.

Red item below that is the coil.

Item in behind that, with the question ? mark on it is your starting solenoid.


As to your tachometer connection, it matters what type you have. The original tachs (say an old airguide tach) used the connections on the switchbox to send the tach signal. Newer tachs expect the signal to come driectly from the rectifier. What model tach do you have ?

 

[AMD Rules]

Re: Merc 1150 tachometer installation

The attached image may help: