I found out my problem and maybe the answer will help someone
I have a '95 force 120. I've had it for 2 months and just found out what is causing it to smoke, idle rough, and die when I put it in gear. The motor has always run badly at idle and run fine at WOT (never hesitates - always had good power and top end speed.) But when I start it it smokes like CRAZY and runs very rough - as though there is no spark in one cylinder or something. Just like many other descriptions of this problem I have to quickly throw it into gear and rev the engine to keep it from dying when getting out of neutral. My thought process (with a little help from hindsight) was as follows:
I had done a full check of the electrical system and found a defective stator. Switched from the 9 amp to a 16 amp stator from seiler marine. Boat started stronger but didn't fix the smoky idle problem.
Because I had an older battery and sometimes the starter sounded weak I switched from a Megatron deep cycle battery to 2 new batteries in parallel- each with 500 cold crank amps for a total of 1000 and what a difference. I should have done that from the beginning - Starter can run all day without draining the battery - still no fix to the idle problem.
Checked (and changed) the plugs - they were wet and oily but I didn't know if that was due to recently flooding the engine or the smoky idle prob.
Adjusted the carbs - setting the idle mixture screws to 1&1/8 turns from light seat, made sure the floats were parallel to the bowl, made sure the throttle plates fully closed, adjusted the throttle linkage and throttle cam as described in the manual, checked the reeds. Everything OK. But the next time I took the boat out I ran it at WOT for 10 mins then noticed the problem of dying when putting into gear was worse.
That was my first clue that I had a carburetor problem.
Finally - the fix
This model motor does not have a choke but rather a "fuel enrichment solenoid." I guess that when I push in the key during start to engage the choke, the fuel enrichment solenoid opens and allows more gas to flow directly into the carburetors past the throttle plates. The manual says to test it by disconnecting the hoses from the the f.e.s. and blow into them. When you depress the button on top of the f.e.s. air should flow. When you release it the air flow stops. In my case I could blow through it both when pushing and not pushing the button - the valve in the f.e.s. is defective. Replaced it and voila - problem fixed. What was happening is that the "choke" was always on causing the problem in idle.
Chuckieman, welcome to iboats and congrats on the fix.
The only problem I have is your battery setup. It won't hurt anything, but 1000cca when only 400mca are needed, is pure over kill. More than likely the battery problem was that you had been using a deep cycle battery instead of a starting battery. And now you have 2 batteries rated in cca. A real marine starting battery is usually rated in mca, but not always.
thanks for your replies roscoe and jerry.
I will go back to 1 starting battery instead of 2 in parallel - no need to cause unnecessary problems.
And one other thought. I believe that one of the reasons that the motor was running OK even though it had a defective fuel enrich solenoid was that adjustments had been made to the carburetors prior to me owning the boat. It's just a guess but I bet the previous owner noticed a problem and adjusted the idle mixture screws to lean the mixture. When I checked the idle mix screws they were not at 1 & 1/8 turns out.
I wonder how many problems go unfixed because of "mechanics" - even pros at the shops - not properly diagnosing the true problem but rather making adjustments to make the engine run better in the presence of an undiagnosed problem.
ps - please don't take this as my thinking my fix was because of any mechanical ability of mine. My fix was due to my manual and good fortune. When I first got the boat I hooked the battery in reverse and damaged the electical system (thank you Force for that fuse you installed) & when I was hooking up the 2 new batteries in parallel I touched the contacts together and vaporized a connector. "Even a blind hog stumbles onto an acorn once in awhile."