wiring without the harness

[glowbox]

greetings fellow iboaters,

i just installed a radioshack rectifier in place of my old burnt merc one. tach was never hooked up to the old one. i am wanting to hook the tach up to the new one. problem: how do i get the send wire from the tach to the rectifier? seems the tach wires coming from the front of the control box arent working so that isnt an option at this point. am i supposed to just drill a hole thru the wrap cowl and leave slack for steering? sounds like a redonkulous question but im stumped on how to get my send wire from the tach to the rectifier..

thanks, glowbox

 

[Moody Blue]

Re: wiring without the harness

What motor year/model? What controller?

Have you verified the tach wire is no good or just assuming it is not?

If needed, I would run the wire alongside the shift/throttle cables. Place the wire through the same grommet that the shift/throttle cable pass through the cowling and tie wrap it to the cables for security.

 

[glowbox]

Re: wiring without the harness

What motor year/model? What controller?

'75-'76 merc 1150 i6. seems to be the original controller.

Have you verified the tach wire is no good or just assuming it is not?

i checked the white(ign?) wire at the front of the controller for continuity and it had nothing with the key on. i realized i was grounding on the wrong battery after thinking it over. after grounding on the starting battery it had juice. just before writing this i ran 3 new wires from the plug in front of controller. green, white, black and connected them to the tach.

from what ive read around here i believe i need a tach that has a 6p setting. the tach i just plugged in has 1-5 on the back and the needle only moves some when cranking but stays at 0 when running. this means the tach will not work, right?

 

[Chris1956]

Re: wiring without the harness

Glow. The brown wire is the tach signal wire. It should be connected to one of the yellow stator wires. a standard outbaord tach (Teleflex, Faria...) will work with that motor. The three wire harness from the front of the MerControl is the correct one.

I did not understand you description of "grounding the starter battery", so I cannot comment.

 

[glowbox]

Re: wiring without the harness

The brown wire is the tach signal wire.

the three wires i have coming out of the front of the control are green, white and black. maybe the black is really brown?

It should be connected to one of the yellow stator wires.

i just put a new rectifier in and the only wires hooked to it were and are: 2 yellow wires from stator, 2 red and 1 black. is the brown (black) wire from front of control supposed to come out of the harness and connect to the rectifier or does one of reds coming from rectifier tie into what ends up being brown (black) at the front of the control?

the tach i just plugged in has 1-5 on the back

will that tach work for me if i get it wired correctly?

 

[Chris1956]

Re: wiring without the harness

I am not sure about the wire colors on that motor. They are non-standard. I have a '77 Merc 1500 IL6, and your wiring colors are different than my motor, so I suspect your controller is newer, aftermarket or something else.

I would check the tach plug on the controller with an voltmeter. The two vertical slots should be +12VDC and ground. The horizontal slot is tach signal. In your case, I would verify that by measuring the resistance on the horizontal slot wire to ground with the tach signal wire connected to the rectifier. Now disconnect the tach signal wire and see if resistance goes to zero.

 

[Chris1956]

Re: wiring without the harness

Glow, Did you install an new three post Mercury Rectifier, or an aftermarket 4 terminal rectifier? The 4 terminal rectifier needs to be gounded or it will not function and will blow out. Tht Merc 3 post rectifier gets its ground when you bolt it to the cowling support.

I cannot predict if your tach will work. You might look up the make and model on the manufacturer's web site and see if it is compatable with Merc Motors.

 

[glowbox]

Re: wiring without the harness

Did you install an new three post Mercury Rectifier, or an aftermarket 4 terminal rectifier? The 4 terminal rectifier needs to be gounded or it will not function and will blow out.

its the $3.29 4 terminal from radioshack. i ran the ground wire to the same bolt that the (-)battery cable is grounded to on starboard side inside the wrap cowl.

my tach is a kysor/medallion with 3 post on back: (I) , (G), (S). i am assuming ignition, ground, and signal.

ill look into the specs on their website. thanks for the advise.

 

[arsenalpsu]

Re: wiring without the harness

that radio shack one migh blow out b/c it can't handle the voltage your stator will put out at WOT,(if it's the one i'm thinking of) I used this one....http://www.allelectronics.com/index...query=35_A_200_PIV_BRIDGE_RECTIFIER&x=27&y=10 and haven't had any troubles.

 

[Chris1956]

Re: wiring without the harness

Glow, The 25A Radioshack full wave Rectifier will handle anything that motor can put out, and then some.

 

[glowbox]

Re: wiring without the harness

Glow, The 25A Radioshack full wave Rectifier will handle anything that motor can put out, and then some.

which rectifier you talking about here? the one i put on or the one arsenalpsu linked to? the one i put on is 25amp and i think 50 volts. 50 volts may be to small from what ive been reading but im gonna give it a shot. it was only $3.29.

im also going to physically run a wire from my tach to the rectifier and see if that makes it read.

ill post the results.

 

[milmat1]

Re: wiring without the harness

The rect. Will have a Current rating (yours 25 A). And a Max Voltage rating. I dont know if you could hit 50 V + At High RPM or not ?? I would put a meter on it rev it up and get an idea anyway..

 

[Gomer50]

Re: wiring without the harness

I run those Radio Shack rectifier on my 80 horse Merc. no Problem, and only for a couple of bucks. 2 wires from the Stator, tach wire hooked to 1 of the stator wires. 1 12 volt + and the 4th prong grounded out to the front cowl. Works like a charm.

 

[ENSIGN]

Re: wiring without the harness

When did radio shack start making mercury parts?

 

[glowbox]

Re: wiring without the harness

ok so it turns out the only thing the wires coming out of the front of the control are good for is a handy switched +12v and a handy ground. the signal wire is worthless. i ran one from the rectifier and my tach read instantly.

now that thats done, on to the next problem.

thanks guys.

 

[Chris1956]

Re: wiring without the harness

The charging voltage on that motor will never reach 50V, as long as a battery is connected, and the connections are good.

 

[glowbox]

Re: wiring without the harness

thanks chris, good to know that i got the right rectifier!

looks like im idling at about 1500! from what ive read i need to be around 850..
i thought it sounded a little fast.