Paul,
Thanks for your help. This list has been a great resource for me and I appreciate the time and effort you and folks like you put into it.
Unfortunately, I'm in Guatemala - no dealer, no parts. I'm going to leave it in forward and forget about it for now - at least it's working. Seems to me that a marine outboard ought not to have corrosion problems like this, but that's just my opinion. The lower unit does have oil - new about 3 weeks before we left. I'll check it for water. I have a new impellor kit, so I'll probably break it down pretty soon to R&R the impellor - maybe something will jump out at me then.
Other issues - the high points:
1) Rubber seal between cowling and engine - it shrinks over time I assume due to heating / cooling, and since it's glued to the inside of the cowling, it's difficult to get it reattached and get a good seal. I finally gave up and used some screws and big plastic "washers" on the inside - works fine now. Non-critical, but annoying nonetheless.
2) Stalling in rough water - runs great in flat water (when it's easy to row) and stalls in rough water (when it isn't as easy to row). Added tilt to the engine and it got marginally better. Added more and that may have improved it a bit more, but it still does it. I make a point of keeping the tank full and that seems to have helped some, too. All that being said, it's a lot better than it used to be, and if this was the only problem, I could live with it.
3) Drain screw in the bottom of the float chamber - it's frozen in place. I've never had a problem with a jet or drain plug on a carb before - I suppose I may have overtightened it, but I'm usually really careful about stuff like that. Seems like that happened after not exercising the screw for a few months. A new float bowl and screw will solve that one for me. Until then, I just pull the carb every time I need to drain the bowl.
4) Fuel issues - the majority of problems I've had with the engine have been fuel related. It takes a lot less to plug the tiny orifices in a small 4-stroke than it does a small 2-stroke. Clean, quality fuel can be difficult to find, and as a result, I've had to really improve my refueling regimen. The best thing I did to date was insert a small inline fuel filter w/ a replaceable element. The engine will still run badly or cut out altogether at random times, but it runs for longer and much more reliably than before I installed the fuel filter. My next outboard will have an external fuel tank so I can insert a water seperating fuel filter inline between the tank and the engine.
5) Ignitor - the ignitor failed while I was at anchor in Miami. Luckily the engine still had acouple of weeks of warranty left on it, so I didn't have to spend about 25% of what I paid for the whole engine on a new one.
6) Fuel tank - about 6 months after purchase, the tank started leaking. It was replaced under warranty - apparently there was a problem in the design or manufacture. About three months ago the tank started leaking again. I guess the heat in the tropics was too much for it. I found two stress fractures and sealed them w/ JB Weld, not having access to a plastic welder. Works great unless I tighten down the air bleed screw in the cap - then the pressure builds and pushes a small amount of gas out. Since it rains almost daily here I've addressed this by leaving the thumbscrew slightly open and inverting the top 1/4 of a plastic drink bottle over it. This is held in place w/ small bungee cord attached to a couple of the cowling seal screws I installed in section 1. It's a real Rube Goldberg setup that actually works quite well since, with the bottle cap off, the bottle doubles as a funnel.
None of these is totally out of line on its own and I've tried to keep a good attitude about it. But cumulatively... I gotta tell you - I think a new outboard ought to be a lot more trouble free than this one has been. I don't believe it's ever run longer than a month w/o something happening. I'd hoped for several trouble-free years of use, but that didn't happen by a long shot. I think it would be fine as a kicker for weekend use in the US where parts are available - if one pays the strictest attention to fuel quality. However, I don't recommend it as a primary tender engine for full-time liveaboard cruising. I'm going to continue muddling along as best I can, but I can tell you right now that my next outboard will not be a Tohatsu 3.5 hp 4-stroke.
At any rate, thanks again for your help,
Mark