90's Mercury 40hp, 2 stroke, 4 cylinder - Bottom Carburetor Issue

[MN Eric]

Hello All,

I recently started an outboard that had been sitting for 2 years (was put away running). I used some carburetor spray to initially get it running and noticed that there was no response when spraying in the bottom carburetor. (i.e. engine speed remained the same)

This design appears to use 2 carbs, one carburetor for the upper two cylinders and the other for the bottom 2 cylinders.

I am not a outboard/2-stroke guy so help me out - could the reeds be 100% stuck closed to cause such an issue? Crank seal sucking air versus the carburetor cause this? Are the coil packs arranged (shared) such that spark could be out on the bottom 2 cylinders?

Regardless, I will be looking into this engine more this weekend (checking spark, spark plugs, etc.) however, I wanted to ask about this bottom carb issue, since it seemed very odd to me.

Thanks Guys!

 

[racerone]

Not a reed problem.

 

[MN Eric]

Thanks for the quick response racerone!

I guess I have never 'sprayed carb clean' and not have it be spark related (please dont be a compression issue) - just seems odd since it was put away running that spark would go out on two holes.

Also, it did seem to idle down and run/rev decently with 'earmuffs' on.

Any other recommendations or things to check for this weekend???

 

[Canufixit2]

Try starting fluid in the bottom carb to see if the RPM changes.
Confirm spark on all plugs.
Disconnect each spark plug one at a time and re start - see if difference in stat.run / rpms.

IF you have a decent spark on all cylinders I'd then think the carbs are gunked up. JMO.