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1976 Merc 850 No spark

J

jrodcat

New member
This outboard sat for nearly 4 years. Ran fresh fuel and started up in barrel yesterday, ran like a champ. Today I cant get any spark. WTH? Any suggestions where to start troubleshooting? switch turns over motor, fuel definately getting in, but no spark. Help...:(
 
Check kill circuit.Disconnect the mercury tilt switch,small round barrel connected to orange wire on switch-box,try again.
 
Later Mercs use a black/ yellow tracer wire to the kill switch and tilt switch. Disconnect it and see if that helps.

Jeff
 
that's a cool wiring diagram. Im sure it will come in handy. Thank you for posting it. So I got home and tried starting it and wiggling the switch it cranked right up. As I wiggled it more it cut out rather hard. I looked under the dash and there's a lot of frayed wiring.
 
Does the start wire go through a neutral safety switch? Eliminating the safety switch is inherently dangerous if you start it in gear at high rpms. Being on the dash it likely has been moved from the control box where the safety switch is. Just something to keep in mind.
 
You're right. It has definately been re-engineered. I must say though, it's been like this since I bought the boat. Never an issue. I'm carefull though and very aware of the neutral. I dont even like the power on full throtle, I just like to cruise along slowly. But I do think its the switch since it will start if I wiggle it around. I may just clean up the wiring and see what happens.
 
Take your time and make sure everything is correct I would even try and get the neutral safety switch working as well. All it would take is two wires from the switch to the back of the ignition and interrupt the yellow start wire to the motor.
 
yea. I'm going to go through all the wiring this weekend. theres too much frayed wire. Even at the battery terminals. I put a fresh RV deep cycle batery on it so I'm not worried the battery is bad, but there's other shorts going on because I can see all the wiring breaking apart. Maybee time for a new (or used) wiring harness.
 
This one is resolved. It was definitely all the wire cracking and causing shorts. I've spliced where I can and it purrs like a kitten (more like roaring). I'm going to look for a decent wiring harness but for now, I guess I'll just keep re-wiring what I can. thanks for the diagrams and all the suggestions.
 
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