Johnson 50hp 1987 Missing Tach Sender Wire

[Pontoonhorn]

I'm trying to rewire my mom's boat and everything is just about complete but I can't find the Tach wire running from the engine to the tachometer..

There is grey wire comming off the back of the tach gauge (S) connection but it been cut like many of the other wires.... But is missing from there to the engine..

Could it be running with/inside the control/ignition wire harness...?

Or do they normaly run by their self routed outside but along with the control wire harness from the motor to the console?

I looked and there is no wire coming from the motor but the control/starter wires ect..


I know it's suppose to be grey... But the color code was long since screwed up on this boat but I've got everything else figured out... fuel sender.. Water pressure ect...

Now the tach has no apparent sender wire from motor...?

I'm no boat motor tech but is there anywhere I should look on the engine to find a missing sender wire...

I think it could have been disconected and or cut unless it inside the ignition harness???

Is it hard to find the tach wire output connection on the motor so that I can replace it a run a new wire to the tach?..

Or from what I've read, find the wire or connection point from the rectifier on the motor... so I can run a new wire

Thanks in advance for any help.....

 

[Pontoonhorn]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

TTT... I've read it was by the charging system?

 

[ezeke]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

The gray wire should be in the main wiring harness, running into your remote control. What kind of control box do you have? The standard side mount has a pre-wired 3 wire tachometer plug below the ignition key.

If you need to run a new wire from the engine, you should have 3 yellow wires on the terminal block: one solid yellow; one yellow w/blue; and one yellow w/gray. Connect your new gray wire to the yellow and gray wire.

 

[Pontoonhorn]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

It's an OMC side mount.... The input is 2 small hard black input wire from engine and 1 large black hard input...

Then the two pink outputs wires/plug to the console... below the key..

I'm not at the location but it has two pink wires below the ignition key that run into the console....Not three... One is for sure the key on power output for the gauges..



The other only had 6 or 9 volts (I can't remember) and I have it terminated currently... I was thinking maybe that was the missing S Tach wire since it has that odd voltage....??

All other wires on the boat have 13 volts...


I read where it sould have a gnd, pwr and tach out... That is not the case..


Like I said it has two pink wire out..

 

[Pontoonhorn]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

Thanks for your help Ezeke..... I'm driving back to my mom's to see what I can find...

 

[Pontoonhorn]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

The gray wire should be in the main wiring harness, running into your remote control. What kind of control box do you have? The standard side mount has a pre-wired 3 wire tachometer plug below the ignition key.

If you need to run a new wire from the engine, you should have 3 yellow wires on the terminal block: one solid yellow; one yellow w/blue; and one yellow w/gray. Connect your new gray wire to the yellow and gray wire.

There is three holes in the plug but only two with wires coming out... Both pink... Missing one wire..

Should there be and odd voltage present with the key on from the tach sender wire and the motor not started?? Like 8 or 9 volts...??

Also is it suppoose to be a power, tach sender and ground as the three wires in the plug below the ignition key...????

Thanks in advance for any help..

 

[ezeke]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

The wires are extensions - the plug has three female connections; see the diagram here:

http://www.maxrules.com/graphics/omc_pics/REMCONTBOX.jpg

 

[Pontoonhorn]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

Thanks Ezeke..


One more question if you have time....

Should there be a voltage on the tach sender wire with the key on but engine not started..

 

[ezeke]

Re: Johnson 50hp 1987 Missing Tach Sender Wire

The gray wire gets signal from the ignition system, which should not be doing anything unless the engine is running.

If you apply any voltage at all to the gray wire externally, you will instantly destroy the recifier, so keep the battery disconnected while setting up and use an ohmmeter to check for continuity.