1974 85hp mercury ignition problems

JDSbama

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Oct 1, 2013
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Hey guys, I just made this account because I am running into some problems with my 1974 Mercury outboard motor's ignition. A little over a year ago my granddad gave me his boat which had been sitting in a shed for probably around 8 years. right after i got it i started working on the motor. i replaced the fuel lines had to buy a new wiring harness and a few other smaller things and had the boat running. It ran well for about a year until just yesterday i tried to crank it up before duck season got started. I turned the key and everything seemed normal (doesn't normally crank on the first try anyway) but when i turned the key to off the motor was still getting power and trying to start. i even took the key out of the ignition but it still kept trying to crank until i unhooked the motor from the power supply. my first thought was there was a problem with the ignition switch so i unhooked all of the wires and took it off. I haven't had time to replace it yet but when i hooked the motor back up to the battery it was still acting like the key was on. I may be wrong but i thought if the ignition switch was the problem and i took it off then it would at least stop making the motor act like that. Could the ignition switch still be the problem or is it most likely something in the wiring? I do not have much experience working on boats so any advice would be more than helpful! thanks!

Davis
 

Faztbullet

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Joined
Mar 2, 2008
Messages
15,570
Re: 1974 85hp mercury ignition problems

Sounds like a stuck solenoid......
 

JDSbama

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Oct 1, 2013
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Re: 1974 85hp mercury ignition problems

Oh ok. Thanks! Would that be hard to fix? If not how would i go about fixing it or testing to make sure that is the problem?
 

jbjennings

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Jul 18, 2007
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3,903
Re: 1974 85hp mercury ignition problems

Totally easy and about a 20 min. job. I would take apart and clean all the connections in that electrical system if it were me, in order to avoid other problems cropping up. You may take that solenoid off, tap on it and get it working again, but over time they get corrosion and such and just need replacing every so often. If it's the original to the motor--it's about time.
JBJ
 

JDSbama

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Oct 1, 2013
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Re: 1974 85hp mercury ignition problems

Ok thanks so much! I'll give it a shot!
 

frederickk

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Jul 22, 2014
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Have you checked the condition of the wires on the back side of the plug for corroded wires
 
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