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Engine won't shut off 1991 90hp

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Rob Merc

New member
I have a 1991 mercury 90 HP 3 cylinder.I have the in dash 6 wire switch.motor starts great But when I try to turn the key switch off it some time won't shut off and sometimes it take a little time in the off position then it shuts off.I figured it was the switch,so I ordered a new 6 wire switch and installed it.But Its still doing the same thing.I took off all the ground wires and cleaned them, thinking maybe it was corrosion but still no help.I looked in my Selco Manual but I can't find any information on it.I'm thinking maybe a kill switch or something in that area ,but thats just a guess.Any information or steps I should take,or switch tests any thing would be helpful at this time.Thanks in advance for any info.
 
Re: Engine won't shut off

Rob Merc said:
I have a 1991 mercury 90 HP 3 cylinder.I have the in dash 6 wire switch.motor starts great But when I try to turn the key switch off it some time won't shut off and sometimes it take a little time in the off position then it shuts off.I figured it was the switch,so I ordered a new 6 wire switch and installed it.But Its still doing the same thing.I took off all the ground wires and cleaned them, thinking maybe it was corrosion but still no help.I looked in my Selco Manual but I can't find any information on it.I'm thinking maybe a kill switch or something in that area ,but thats just a guess.Any information or steps I should take,or switch tests any thing would be helpful at this time.Thanks in advance for any info.
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There has been another problem recently that was happening before this ,that might have something to do with it not sure.I can run it out in the river for some about of time minutes - hours different ever time it happens.Runs great for minutes - hours then all of a sudden it stalls and I can't get it started.have to get tow in. Then play with it at home to get it started haven't figured it out yet.but I know its not fuel issue cause I rebuilt carbs n fuel pump 2-3 months ago.Figured I throw that in thinking maybe it some electrical or switch problem.
 
Re: Engine won't shut off

As to the won't stop problem...I experienced that some long time ago. Seem to recall a yellow wire had broken in the area where the bundle of wires came thru the back deck going to the motor. Seems the yellow wire causes a ground to kill the engine.
 
Re: Engine won't shut off

Your right BIGFLAT the yellow and black wires some type of kill switch,if I run a ground to that wire on the switch box it shuts it off right away.and I cleaned the ground on the switch [little cylinder shaped] that is hooked to the yellow black wire.May be that switch went bad but I don't know how to test it.Thanks for the reply.
 
Re: Engine won't shut off

your black with a yellow tracer wire is your kill wire, it goes to ground when you turn the key switch off and shorts the switch box (power pack) out. Test to see if this happens. If this does go to ground when the key switch is turned off, both at the switch and at the power pack and the engine still remains running, replace the power pack.
 
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