86 Merc 50 hp 2 stroke idle fine, WOT fine, but stalls when in gear

[fishin'musician]

Hi all,

I've read many posts with similar issues, so this may sound like another of the same problem, but I don't have a problem at WOT.

I have an '86 Mercury 50 hp 2 stroke, which had been sitting up for about 15 yrs. I recently had a major tune-up, which involved the following:
100 hour service/Tune-up/Impeller maintenance
Removed Auto-blend (doing 50:1 pre-mix now)
Fuel pump diaphragm kit
Carbs removed and cleaned
New Fuel line
Flushed fuel tank
Water pump kit
Repaired wiring from the switch box
Spark plugs

With all of that done, I'm having problems with the engine stalling out when I put it in gear. It's not stranded me yet, but it makes it very difficult to maneuver around a busy launch dock.

It cold starts fine, idles fine (about 1100 rpm) and gets on plane just fine. It will do about 30 mph @ 5500 rpm, no problem.

However, if I've been fishing in a cove for a bit, then start it up to move to another location, it will stall when I push it into gear. Once this stall happens, it doesn't want to start up again, smells like I flooded it and requires that I let it sit for a few minutes before trying again.

I've been able to workaround this by pushing the throttle up very quickly to get going, then pull it back to a slower speed (5 mph speed limit in the coves and of course around the dock).

The carbs were cleaned, but not rebuilt. And now, after reading some of the older posts, I'm wondering if it could be a dead cylinder issue, though it has no trouble at WOT.

Any feedback will be greatly appreciated!

 

[Chris1956]

Mercs do that all the time. The simple carbs that were used needed for the idle mixture to be set rich to allow acceleration. This caused marginal idle quality.

You can try to adjust the carbs a bit more lean. Be sure to use a fresh fuel mix and warm up the motor well, and take your time.

Try for the leanest idle mixture that still allows acceleration. It is likely the bottom carb can be set a bit leaner than the top carb.

Or do what the rest of us do. Put her in gear and accelerate just a bit to keep her running, in one smooth motion. It becomes second nature after a while.

 

[fishin'musician]

Hi Chris - thanks for your quick response. I plan to put it in water this weekend, put it in gear still tied to the dock and adjust carbs. After I had the big maintenance job, the boat ran fine for a couple of trips on the lake, then it suddenly deteriorated to the current stalling issue. Totally new issue that I've never had before.

This is a 3-cylinder engine, and I don't understand why they used only two carbs. Which one feeds two cylinders, the top or bottom?