'71 merc electrical question

[clamneck]

I just picked up a used boat today that has a 1971 (I assume due to the serial number) 650 65HP 4 cyl on it and it is said to have a certain electrical problem. What I'm told it's doing is starting with the key sometimes and not getting anything at all at other times. I know it turns over cause we jumped it at the starter cause the key wouldn't work. can someone clue me in to what the problem is and please tell me it's a cheap fix . I'm alright with electrical as long as you don't use really big words. any help would be greatfully accepted. oh, afterthought, the guy i bought the boat from said the previous owner said it may be the trigger. Is this a possiblity and please tell me know cause the dang thing cost an arm and a leg.

 

[Laddies]

Re: '71 merc electrical question

Ck the pins on the plug in, if the choke clicks you have power to the switch and it is working, if it is alright use a volt meter and see if you have 12v on the white termainal of the swichbox,

 

[tashasdaddy]

Re: '71 merc electrical question

i have a '71 1350. had to put new wiring harness, internal and external. when i opened the control box every thing was bare. all the insulation was off the wires, and very corrided. the engine wasn't much better. not runs like brand new.

 

[canadian_fisher]

Re: '71 merc electrical question

67thunderbird

I had a "flaky" ignition and kill switch that was causing intermitent start / stops. To diagnose if you have Engine versus Boat wiring issues, try disconnecting the BIG main wiring harness that connects motor and boat.
Now try jumping the motor at the Selenoid and see if she starts.

**WARNING** .... you'll need to re-connect the plug to stop the engine (or try to choke it out manually).
This works much better as a Two-man operation, speaking from personal experience.

Good Luck........ CF

 

[clamneck]

Re: '71 merc electrical question

Ck the pins on the plug in, if the choke clicks you have power to the switch and it is working, if it is alright use a volt meter and see if you have 12v on the white termainal of the swichbox,

By the choke clicks you mean push the choke button, right? I'm new to this merc system and I don't know all the functions yet.

 

[clamneck]

Re: '71 merc electrical question

i have a '71 1350. had to put new wiring harness, internal and external. when i opened the control box every thing was bare. all the insulation was off the wires, and very corrided. the engine wasn't much better. not runs like brand new.

Thats how my last boat was. I replaced all the wiring and then come to find out the transom was shot. I'll see if I can check all these things tonight.

 

[clamneck]

Re: '71 merc electrical question

67thunderbird

I had a "flaky" ignition and kill switch that was causing intermitent start / stops. To diagnose if you have Engine versus Boat wiring issues, try disconnecting the BIG main wiring harness that connects motor and boat.
Now try jumping the motor at the Selenoid and see if she starts.

**WARNING** .... you'll need to re-connect the plug to stop the engine (or try to choke it out manually).
This works much better as a Two-man operation, speaking from personal experience.

Good Luck........ CF

We tryed that just before I bought it but we still had the harness on and it probably would have started if we had some fuel to it. By the way, can someone tell me how to read a voltmeter or what I should have it set to?

 

[Laddies]

Re: '71 merc electrical question

Set your meter to 20 volts DC it varies from meter to meter so as long as you arer as close to 12 volts as possible its ok

 

[tashasdaddy]

Re: '71 merc electrical question

with the harness unpluged the choke button won't work. if you remove the black top cover, on the front top of the engine should be a knob which is the manual choke.

 

[clamneck]

Re: '71 merc electrical question

Set your meter to 20 volts DC it varies from meter to meter so as long as you arer as close to 12 volts as possible its ok

Thank you very much, I never could understand those things.

 

[clamneck]

Re: '71 merc electrical question

with the harness unpluged the choke button won't work. if you remove the black top cover, on the front top of the engine should be a knob which is the manual choke.

ok, I found the manual choke knob, should it be up or down? I don't think I heard any clicking from either that or the choke on the control unit though I don't know if I was doing it correctly. My son and I were working on it tonight and we discovered the symtoms for ourselves. Here it goes: we put on 2 different batteries to see if it was a battery problem but both acted the same way. you turn the key and you get a few medium to loud clicks coming from somewhere by the silinoid(?) and then nothing. you turn the key again and you get maybe one click and then nothing. you turn the key again and nothing at all until you twist the main wiring harness plug and then u turn the key and the cycle starts all over again or it just does it once and then nothing. beforehand I pulled the plug off and cleaned it and spread the male pins so they would get good contact and I redid it after going through all of this but the same thing was happening. I know that it will turn over cause we did a compression test by jumping the starter so does anyone know what this could be? Also, I found a disconnected wire on the engine side of the harness plug. the wiring group has a brown, red, white and what looks like grey wire with that grey wire diconnected. Does anyone have a wiring diagram or tell me where it goes? The rest of the set goes to some block looking thing in the front of the motor where the top black motor cover latches on to.

 

[ricksrster]

Re: '71 merc electrical question

The grey wire goes to your choke solenoid.

 

[tashasdaddy]

Re: '71 merc electrical question

send me an email "tashasdaddy@comcast.net" request wiring diagram 71 65hp i need serial # as i have 3 different diagrams for the 65.

 

[clamneck]

Re: '71 merc electrical question

The grey wire goes to your choke solenoid.

thank u very much, but where is the choke solenoid?

 

[clamneck]

Re: '71 merc electrical question

send me an email "tashasdaddy@comcast.net" request wiring diagram 71 65hp i need serial # as i have 3 different diagrams for the 65.

e-mail sent and thank u very much.

 

[tashasdaddy]

Re: '71 merc electrical question

choke solenoid is behind the panel the manual choke rod is on. looking at the engine from the back go to the left side close to the front where all the wires are at the very top is a round solenoid it has nut on it . put the grey waire under the nut. then turn your key on and push your choke button you should her it click.

 

[tashasdaddy]

Re: '71 merc electrical question

starting procedure when you are ready. put ear muffs on the water intake on the lower unit, with hose attached. turn on water. connect fuel line. pump bulb until hard. push choke button and hold turn key to start, let it turn over several times. go back and pump bulg again until hard. push and hold choke turn key to start. if it is tune right it should start in 15 seconds or less... if not let's find out why.

 

[clamneck]

Re: '71 merc electrical question

starting procedure when you are ready. put ear muffs on the water intake on the lower unit, with hose attached. turn on water. connect fuel line. pump bulb until hard. push choke button and hold turn key to start, let it turn over several times. go back and pump bulg again until hard. push and hold choke turn key to start. if it is tune right it should start in 15 seconds or less... if not let's find out why.

U the man, got the diagram, thank u very much. It's printing now. Let me take a look at and doublecheck the wiring first. any idea's why it's clicking and only does it when u mess with the wiring harness?

 

[ricksrster]

Re: '71 merc electrical question

Loose connection or broken wire, or Cracked insulaion. Looks like a wiring problem.

 

[clamneck]

Re: '71 merc electrical question

I'm working on it now and I reconnected the choke wire. No noise when the choke is pushed. The first time I turned the key it wanted to turn over and after that just clicks or one click.