Mercury 110 9.8 problems

robsd

Seaman Apprentice
Joined
Feb 18, 2002
Messages
37
Gentlemen,

It's been a while, this little 1970 motor has been working great over the past 7 years runningup and down the Trinity river. But not it has given up on me. It's been in the garage for the past 9 months or so. Cowl on, closed up. It's always fired up after a few month sitting with no problem. On Saturday I mixed up some fresh gas and it did start but didn't run very well, wouldn't stay running, wouldn't idle, it would die when I put it into gear (running is a water barrel). Then nothing at all. I took apart the carb, it looked good(I did replace the hollow plastic float a couple years ago). I replaced the bulb and fuel lines with new (I always have a spare bulb!!). Pulled the plugs and no spark. After some more wasting time I gave up. I brought the whole thing home and tore into it yesterday. I pulled the flywheel and found light oil around the points. And the point gap was maybe .005. I cleaned that up, filed and opned up the points a bit (not sure wat the setting is, I set them about .015-.020). Put it all together and am not getting serious spark across the flat style plugs. BUT...when I open the throttle, I get no spark. the system I have is 2 points, and the 2 orange coil packs off the back. After some more pulling and no firing I noticed the plugs were dry as a bone...but I was getting some fuel overflow out of the carb. The overflow is just a few drops after I stop pulling, not a continous flow. I pulled the choke off and tried to feel for suction, nothing. Since it's hard to feel and pull I put a paper towel in front of the venturi. No suction whatsoever. Weird. The engine has good compression, I haven't put a guage on it but it'll wear you out after a short time.

I found on the web some Seloc directions on setting the timing, it has a sticker on the pull starter that says .195 BTDC 34 1/2 degrees. I'll have to figure that out.

Not sure of the point gap so if anyone has that i could use it. Why I lose spark when I turn to WOT is a mistery (it always started best at WOT).

The non sucking carb has me really scratching my head. And the good compression. If I recall a 2 cycle will pull the air/fuel mixture into the crankcase, then it gets pushed onto the top of the piston for firing. My only thought is a crack somewhere or blown gasket and the air is being sucked from somewhere else? And it did run a little bit before I got nothing.

Any help would be greatly appreciated. I use to rebuild engines for a living so I'm handy around them. But this is my first ever boat engine. Only other 2 strokes were dirt bikes when I was young.

Sorry for the long post but the more details the better.

Thanks,
Rob
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Mercury 110 9.8 problems

Point gap is listed at .020

Take a very close look at the wires to the timer plate, check for any chafing/ground, also check with a meter as you move it through its travel, this old the wire could be broken off within and not be visably bad.

Verify a hot spark before moving on to any other problem.Also check the insulator fitting that passes the wire thru to the point. I've had one that the white plastic was (?) burnt/blackened, had a carbon trail to ground on the inside edge between the two pieces such that it could not be seen until disassembled.
 

robsd

Seaman Apprentice
Joined
Feb 18, 2002
Messages
37
Re: Mercury 110 9.8 problems

Point gap is listed at .020

Take a very close look at the wires to the timer plate, check for any chafing/ground, also check with a meter as you move it through its travel, this old the wire could be broken off within and not be visably bad.

Verify a hot spark before moving on to any other problem.Also check the insulator fitting that passes the wire thru to the point. I've had one that the white plastic was (?) burnt/blackened, had a carbon trail to ground on the inside edge between the two pieces such that it could not be seen until disassembled.

Good idea on the meter checking while turning the plate Charlie. You know I have that same black carboned look where passes through to the point. Both exactly the same and I dismissed it as some sort of factory thing. Interesting.

Thanks,
Rob
 
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