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Unplug wiring harness and it runs fine plug back up and no fire.

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Snuffer71

New member
I have read all over and as much as I have read I can't find any thing, maybe I just don't know how yet, anyways if someone can redirect me to a thread or maybe answer my question I appreciate. I have a 86 model 45 mariner and it just stoped running, took it to a boat garage with a 50 horsepower mercury that I bought for parts and the man told me they were both junk and the motor wasn't worth fixing, now I have used this motor in the river all the time, so I couldn't understand how it was junked out, well after looking At these motors for a year I decided to fool with it some not figuring I could do anything with it cause they said it couldn't be fixed cause the cost wasn't worth the motor, it would crank and crank and would not get any spark, so after reading on here for s long time about some of some similar problems, I decided to change the staitor and the trigger off of the two, now I still had the same problem except now the motor ( no crank) or power trim would not work .so then I read to unplug the wiring harness and try to jump it over and I did and it started right up. With amazement I was so excited, so I choke it turn it off, go to key switch and nothing, so i ran a test to my key switch and nothing , no choke, no power trim no power on any of the wires, I ran a hot wire straight from the battery to the red wire and the red-yellow wire and everything seem to work well power trim, choke everything cranked it and it tried to fire once then nothing, unplug the wiring harness and jump it over run great. So my question is it seems to me just like the kill switch or something is grounded how would I check to find this out or maybe it is in my key switch or wiring harness, since the thing runs when the big plug is unplugged, could there still be something wrong with staitor trigger or possibly anything else. I may not fix this thing but I've learned a little more than I used to know. Any suggestions what to do next.
 
If you disconnect the remote control and the engine starts, your problem is in the remote control side of the system. The engine is fine.

Time to get a meter and start checking wires and the ignition switch.

Question, does the boat have a lanyard?
 
Docksidemarineservices said:
If you disconnect the remote control and the engine starts, your problem is in the remote control side of the system. The engine is fine.

Time to get a meter and start checking wires and the ignition switch.

Question, does the boat have a lanyard?
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It has a laynarn switch, It's in the up position, I have tried unhooking the black yellow going to my box on the motor still nothing, I should have Mention that also.i read somewhere that unhooking the black yellow wire from ignition box on motor would eliminate that. I'm going to take the whole key switch out today and try putting the other in. Thanks for the reply dockside marine services .
 
Ok been working on this again decided not to change key switch, so I unhooked the black wire with yellow stripe direct from my power box where as yesterday I hooked it from the switch, for some reason it starts up and works good, so do I need to change keys switch or the kill switch on the motor, I do have another motor so I do have the little switch that Goes on the motor, but I read somewhere that there is how you can kill you power box, any suggestions
 
I would trace out the Kill witch wire(Black W/yellow) and find out where it is grounded. If you disconnect it(Black W/yellow) at the ignition switch and the engine runs, the switch is bad.
 
Thanks, I will unplug it at the keys switch first thing in the morning and try it, if it doesn't run would that mean it is in the keys switch.
 
Humn!! Thanks Chris it's just like a bowling ball just fell on my toe , I see exactly what you mean. Sometimes slow thinkers like me needed it spelled out. Lol, thanks first think in the morning I start looking
 
Snuffer71 said:
Humn!! Thanks Chris it's just like a bowling ball just fell on my toe , I see exactly what you mean. Sometimes slow thinkers like me needed it spelled out. Lol, thanks first think in the morning I start looking
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No Worries. Some people on here never get it.

FYI, if it turns out to be the wire and not the key(ignition) switch, you will want to pin point the failure spot. Where one wire is damaged there may be others.
 
Do not run the engine with the battery disconnected it will cook the rectifier/regulator and stator fairly fast. Just a word of caution. Does the controls have a lanyard kill switch that the clip is missing? Got pics of the control box?
 
I took a pic but can't figure out how to post it.i have ran all the wires all way up to the control, problem is now the screws are so rusted I can't get into the back except the key switch, I found the wire that works my power trim on the up side disconnected, which could be the cause of the problem, but can't get In There to see. So now I'm am really aggravated, and not a place to take it. Since it is running really well with out the kill switch wire connected except for cutting it off without choking, are the away to run a separate kill switch? Or would this cause maybe more problems.
 
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