Merc 9.8 Kill Switch Problem?

d.boat

Chief Petty Officer
Joined
Sep 19, 2008
Messages
520
I have a 1974 Merc 110 9.8 hp. In the recent past, I've replaced coils and switch box because they failed. It's been running really well the past two seasons, starting right up, idling trolling and WOT great.

This season, it usually starts right up -first or second pull choked when cold, first pull when warm. But, sometimes, I can't get it to start for a while and then all of a sudden it just starts right up. When it's not starting, I just get the feeling it's not getting any spark. The plugs are getting fuel, but it's just not firing. Looking at all the connections, they seem to be clean and in place.

I'm wondering if there could be a kill switch issue? This switch has one (brown I think) wire running up towards the flywheel. Does the switch ground that wire when pushed, or does it interrupt a ground when pushed?

The reason I ask is that the connection underneath the rubber piece that covers it inside the hood (as opposed to the rubber covered button outside the hood) looks kind of nasty, corroded etc. I plan to clean it up, but am wondering how I could simply determine if the kill switch or connetion is causing the starting problem.

If it were a bad kill switch and/or connection, what would clearly eliminate that problem - disconnecting the wire from the kill switch or making a solid ground for that wire? Whatever it would be (disconnecting or grounding), I plan to try that next time the thing won't fire up.

Thanks
 

d.boat

Chief Petty Officer
Joined
Sep 19, 2008
Messages
520
Re: Merc 9.8 Kill Switch Problem?

I took a quick look at my OEM service manual, but didn't see a schematic for the kill button. This manual covers so many engines for that era that it is a little difficult to follow though.

Any help or insight at all is apprciated!
 

d.boat

Chief Petty Officer
Joined
Sep 19, 2008
Messages
520
Re: Merc 9.8 Kill Switch Problem?

OK, I did what I should have done in the first place, and checked it out myself. Just for future interest - the kill switch grounds the wire. Mine's OK, which means my spark problem is elsewhere, unfortunately.
 
Joined
Nov 7, 2004
Messages
21
Re: Merc 9.8 Kill Switch Problem?

hey if you have the service manual is there any way you can tell me how to get the whole bottom end off the motor... Digrams would be great ..
 

d.boat

Chief Petty Officer
Joined
Sep 19, 2008
Messages
520
Re: Merc 9.8 Kill Switch Problem?

hey if you have the service manual is there any way you can tell me how to get the whole bottom end off the motor... Digrams would be great ..

You should start a new thread,this is a totally unrelated topic (and I can't help you).
 
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