1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

Laser Boat

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Hi, im new to boating and just got a older 80's model 18ft Laser Bass boat, with Mercury 150 v6 Blackmax. Has a Quicksilver throttle control box w/trim. Just got the boat, none of the gauges or lights etc work, looks like i need to repace all the fuse holders & fuses, reconnect few wires. Will do, but boat hasnt been started in couple years, i just got it, messed with motor for couple weeks cleaning on carbs, new spark plugs, it was turning over for few days, then begun to fire, try to run 5-10 seconds, then finally last nite it fired up & sounds awesome, revs up, iddles fairly smooth on low. felt good about it, then went to shut it off, and nothing happened, even pulled the key out. flipping the toggle kill switch. Kept running, i had to pinch off the gas line for a minute to let it run out & die. Would this just be needing like a new key switch, also the control cables look bad shape, alot of plastic cover peeled off & rusted cables, should i just replace the whole control box/cables.. any input appreciated.
 

Chris1956

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

A 1976 motor probably has the old wiring colors. You do have the ADI ignition with 6 coils right? Your killer wire would therefore be orange or salmon. It needs to be grounded to kill the ignition. The only way to see what new parts you need is by testing the function of the old stuff.
 

oldman570

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

If the gauges, kill switch, and key will not work to stop the motor then you need to check the ground wire from the motor to the switch, and see if it is broken or bad connection somewhere in the harness or the plug at the motor.
Oldman570
 

Laser Boat

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

A 1976 motor probably has the old wiring colors. You do have the ADI ignition with 6 coils right? Your killer wire would therefore be orange or salmon. It needs to be grounded to kill the ignition. The only way to see what new parts you need is by testing the function of the old stuff.

Thank you both for you replys.. Ok ive found my kill wire (black w/yelloew) and found correct location to connect. While motor was running i touched the wire to the connection and it killed it(yay). But after connecting the wire, my motor will not start, i disconnect that wire, then the motor starts fine again. Now before continueing i will say i have 3 more wires not connected yet to anything, i was going to address after this one, but is it possible they are preventing the motor or kill wire to work correct. The last 3 remaining wires i have from my quicksilver box to conect are my PURPLE, SALMON, BROWN W/WHITE STRIPE. Will any of these 3 prevent me from starting and shutting off the motor if the rest are connected?
 

Faztbullet

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

What is your engine as they did not make a V-6 in 1976, they came out in late 1977. The colors you posted sound like you have a old inline. Where is this toggle kill switch? Is it on rear of control box?
 

Chris1956

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

Those combination of wire colors are unusual. You might post serial number and verify it is V6 or inline six.
 

Laser Boat

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

What is your engine as they did not make a V-6 in 1976, they came out in late 1977. The colors you posted sound like you have a old inline. Where is this toggle kill switch? Is it on rear of control box?

Thanks again for replies, well right before signing on again, i remembered about the kill toggle switch, so just went and checked, sure enuff that was my starting problem. connected my black/ylw wire back and flipped the Kill toggle swtch, alls working fine with that now. But for any other input you can give about my remaining 3 wires. heres my info, my motors black mercury case says Mercury V6, Blackmax, thunderbolt ignition. serial number 4589810. Im sure its a V6 though, has 3 spark plugs on one side, 3 on the other. I looked up the ss# on another site, it said 1976 year, so thats where i got that,.. there is no wire hareness connectors coming off the motor, they have been cut off, same from my quicksilver throttle controls. all the wires are tied together & taped off or wire connectors. so the colors on my quicksilver wires i think are newer than my motor and the wire colors from it. like my kill switch wire i just connected was black/yellow from the quicksilver, but on my motor switch box had the orange or salmon colored wire..
my last 3 wires no connected to any thing coming from my quicksilver connector are the purple, salmon, brown w/white stripe. . sorry i have no other info or knowledge of what i have, this is my first boat, just got it, in this condition paid $300 for it, they thought the motor was blown and steering was locked up, ive already replaced the steering cable, cleaned the carbs & it runs great. came with the boat trailer too. so very proud of what i got so far haha.
 

Chris1956

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

OK, It sounds like you have the newer wire colors on control and old wire colors on motor. Not an issue. I do recomend you cripm, solder and then shrink wrap the splices. You do not want them failing on the water. Here is the interconnection specs.

Motor salmon goes to Black/yellow for ign kill; motor white goes to purple for ign accessory; engine black and red are same on control. Engine grey goes to yellow/black for choke; Engine brown goes to grey for Tach signal; Brown/white looks to be trim sender, which you likely do not have; Motor yellow goes to yellow/red for starter solenoid. There is no salmon specified in the control wiring colors. Is it possible tan for the overheat alarm?
 

Dukedog

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

What is your engine as they did not make a V-6 in 1976, they came out in late 1977. The colors you posted sound like you have a old inline. Where is this toggle kill switch? Is it on rear of control box?

Alright there Admiral. Ya need to do some deeper diving. It did come out in '76 Was badged 1750. Was a 2.0 175. Only V6 horsepower available '76 and '77. Model number 1175626. I bought two of 'em that year and started my addiction to tha V6 Merc/Mariner........150 and 200 V6 came in '78.
 

jimmbo

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

The V6s were introduced as 175hp motors in July/August of 1975 as early 1976 models. The V6 150 first appeared in the 1978 model line up.
 

Laser Boat

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

Chris thank you, Looking to connect the purple control wire to my white motor wire, can you help give me a clue to the location of that white wire, Think ive seen one coming into the middle of my outter switch box. would that be it?

Sorry guys one more thing, after i connect this purple wire, should my dash gauges then work (if they are all hooked up) currently during this process none of the guages have worked either.
 

Chris1956

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

The purple wire should get voltage from the red battery power, at the ign switch. The power runs from the ign switch to the motor, not the other way around. Your motor probably does not have a white wire on it, as it really doesn't need battery power for anything. There looks to be a white wire that goes from one switchbox to the idle stabilizer, however that is different...

if your gauges don't work look to the ign switch or dash wiring.
 

Laser Boat

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

Appreciate everyones patientance as im getting "BOAT" fimiliar.. ok, Think i understood about the purple getting ignition power at the switch, but all post ive read about wiring has said to connect the purple wire to purple on motor or white in my case with older motor. and the purple was for like dash lights, aux. stuff to come on with ignition. so i was thinking what ever it connected to some how came back to my dash or guages, etc. if i dont need to connect it anywhere by the motor, can i just tie on to it, run it back to my dash for my gauges? currently they are not working. i have replaced all toggles & fuses, wires for the extra stuff, completed, and ive put new wires on my guages, hooked to ground, but havent been able to tie into ignition wire anywhere.
 

Chris1956

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Re: 1976 Mercury 150hp runs, but wont shut off..? key will not shut off motor

Sometims the merControls will have a plug for a tachometer. it will have purple, black and tach sender (grey) wires for gauges and tach.
 
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