1994 120 Force Carb adjustments

[ejs68]

Hello All,
I'm starting to hate boating. Last night we went out fishing. We movedx along at a little over idle speed for about 15 minutes or so before stopping to fish. The engine seemed to be idleing a little rough, so I put it in neutral and gave it some throtttle to clean it out. After sitting for about an hour, we could not get the engine started. After wading through 1.5 feet of muck and weeds for an hour, I got home. I took the plugs out and they were pretty dark looking, like they were fouled. My question is, what is the proper carb adjustment for slow speeds. Do I turn the screw in or out? The manual I have (Clymer) doesn't say, only that the screw should be out 1-1.5 turns.
If I run the boat with muffs on in the yard, what should I be looking for as far as an idle speed and engine roughness? Any advice would be greatly appreciated, as I am at a loss as what to do. Yes, I realize I should have brought an extra set of plugs and tools, but they were left at home right where I forgot them. Spent the night before fighting trailer lights.
Thank You

 

[Frank Acampora]

Re: 1994 120 Force Carb adjustments

Force engines hate to idle, and the surface gap plugs (if you have them on that year) foul like crazy. The quickest fix is to always carry an extra set of plugs. You see: when these engines are cranked to start, the voltage produced is less than when they are running. So a marginal set of plugs will run quite happily at speed but may stall at idle and may not restart the engine. When I am out on the water and see someone having trouble with a Force, the first thing I do is give them a cleaned set of plugs. By the way, you can easily clean the surface gap plugs with a green plastic abrasive pad. Known informally as a "green scrubbee" in the food industry. Use your thumbnail to work the pad into the surface gap and around the center electrode.

You usually start carbs about 1 1/4 turns out from lightly seated and adjust from there. My usual WARNING:--Do not go leaner than 3/4 turn out even if the idle suffers. Too lean melts pistons.

Best to set the idle in the water in forward gear at 700-750 RPM. Neutral in the driveway should be somewhere around 1,000 RPM to yeild 700-750 in gear in the water.

Before you play with the carbs and fuel mixture, because this is a very quick way to ruin a perfectly good engine, just try new plugs and raising the idle speed if it is too low.