Mercurey 110 9.8hp dead hole?

[Wind dog]

Hi all, need some help!


The motor is a Mercury 110 9.8hp with type 2 ignition system. #1 hole (Top cylinder) is dead, ( I started engine with #1 plug disconnected & found no difference in performance then when connected) I checked compression and have 110psi both holes, when I remove the plugs #1 is wet & clean, #2 is wet & black. I have good spark on both (Removed plugs, grounded & pulled on starter rope a couple of times & saw good sparks both holes) I also checked the points as per my Seloc manual.
All this testing was done in driveway with motor in a bucket.
I just replaced the fuel line from pump to carb, I replaced the factory line with hose barbs & hose clamp, The ID of the new line may be larger then factory.
Thanks for reading.

 

[oldman570]

Re: Mercurey 110 9.8hp dead hole?

If the compression is as stated and the plugs fire when out of the motor switch the plugs around and see if the trouble stays with that plug. It might test good when ti is out of the motor but will not fire as it should when under compression. What brand and plug # are you using?
Oldman570

 

[Wind dog]

Re: Mercurey 110 9.8hp dead hole?

If the compression is as stated and the plugs fire when out of the motor switch the plugs around and see if the trouble stays with that plug. It might test good when ti is out of the motor but will not fire as it should when under compression. What brand and plug # are you using?

Thanks for the response Oldman570, they are NGK BUHW-2.

I did switch them at one point and it did not seem to matter. I also tried starting it with#2 plug disconnected & #1 connected, it would not start, with #1 disconnected & #2 connected it would start.

 

[jim j geezer]

Re: Mercurey 110 9.8hp dead hole?

A couple of longshots worth considering:
1. Eyeball the *HELL* outta the #1 plug lead - all the way back to ignition source. Could attaching the #1 lead be stressing that lead enough to break a connection?
2. Install #1 plug and its wire, then turn out the lights and crank it. If you see sparks anywhere, proceed accordingly. You might have to change out a plug wire.

 

[oldman570]

Re: Mercurey 110 9.8hp dead hole?

Try switching the wires that come from under the flywheel to the coils and see if the spark moves with the change. If it moves switch them back to the coils that they were on. Your trouble will be under the flywheel as the points could be bad or the wire from the nonfireing coil might have bad insulation on it and grounding out the coil causing it not to fire if the motor is a older motor.
JMO
Oldman570

 

[Wind dog]

Re: Mercurey 110 9.8hp dead hole?

Try switching the wires that come from under the flywheel to the coils and see if the spark moves with the change. If it moves switch them back to the coils that they were on. Your trouble will be under the flywheel as the points could be bad or the wire from the nonfireing coil might have bad insulation on it and grounding out the coil causing it not to fire if the motor is a older motor.
JMO
Oldman570

Thanks guys I will be checking all these, I'll let you know.

 

[Wind dog]

Re: Mercurey 110 9.8hp dead hole?

So I replaced the plugs, inspected all wires, and did a Sea Foam decarb. I seems to have fixed it.