Update on my Tohatsu 3.5HPIn this review I mentioned that I chose a Tohatsu 3.5 HP outboard to power my TI. I liked the fact that it provided an extra horsepower for about the same size engine as a 2.5 HP. Additionally, it produced the most thrust in comparison tests. It did a great job providing more than enough power for the TI, it would hit the rev limiter at about 3/4 throttle so its full potential was never realized without a higher pitch prop (which I could not find for this motor).
While it had excellent power, it unfortunately severely lacked in reliability. It would sometimes run fine for hours but other times it would stall continuously. I first contributed this to a fuel issue, thinking that there was a problem with the gasoline I was using even though I had carefully selected and checked it. So I then found a top tier gas station that offered non-ethenol. I then further filtered the gas using a water and contaminate separating filter, and then added both Starbrite gas stabilizer and Seafoam to it. Yet no change, the motor would run fine at times and then continuously stall leaving me stranded. Good thing I had the 403.
I began to notice the motor would have trouble primarily on days where the waves were choppy. It also would stall when executing a sharp turn. Both of these conditions had one thing in common, they would splash a lot of water under the motor's cowl. Now you would think that a marine motor would be waterproof, or at least highly water resistant. Not so the Tohatsu. There is a large opening on the bottom of the cowl where the oil plug protrudes. Just above this large opening is, believe it or not, the air intake for the carburetor. So when water would splash onto the bottom of the cowl and into the oil plug opening, it would then be sucked into the carburetor's air intake which then quite effectively stalled the motor or caused it to sputter to an eventual stall. Once water entered the fuel system, it would be very difficult to clear it out and the motor would not run well for quite some time afterward.
This motor, and its Mercury clone, have a history of stalling issues as you can see
here if you read the large number of negative reviews. This, I speculate, may primarily be caused by water splashing under the cowl, although many owners don't seem to realize that could be the real issue, so they focus on fuel and carb issues. This problem is exacerbated on the TI because our motors are mounted on the side of the boat rather than being typically mounted onto a rear transom which provides a better degree of protection against splashing. On the TI, the side mounted motor is exposed to splashing from wave action. Additionally, the rooster tail of water from the prop splashes water onto the side and back of the TI causing even more water exposure to the motor.
I tried covering the hole for the oil plug with Gorilla tape. This made a dramatic difference. I could now execute sharp turns without the motor stalling. However, it would still stall on choppy seas. This is because there is another huge opening where the throttle lever protrudes. Unlike the oil plug opening, this was almost impossible to tape up because the throttle lever needs to rotate up and down and it's right near the very hot exhaust pipe. Yet I tried and it further helped with the stalling, but in the end it proved all but impossible to stop the water from getting in when the splashing was extreme. Enough was enough, I couldn't cure a bad design with a roll of Gorilla tape or any other such first aid. This motor was simply ill equipped to work on a TI. It might be fine for a little boat tender where the user just travelled a few hundred feet to get to his moored sailboat, but it was simply not designed well enough for the all day rigours of operating for hours on the side of a TI in all kinds of seas.
So I'm removing the motor from my TI and returning it to the dealer who thankfully said they would offer a full refund after I explained the problem. At least the motor dealer was superb in this matter.
For use on a TI, I do not recommend the Tohatsu 3.5 HP motor, and by extension its 2.5 HP brother (same design), nor do I recommend the Mercury, Mariner, and Nissan clones of this motor.
So my TI is now once again without a gasoline powered motor, but I'm getting along perfectly fine with just the Torqeedo. The only thing I do miss is the extra speed because I like to travel very far distances and get there more quickly due to the fact that I travel on a very large body of water and far away sights are tempting. So I have not yet given up, I will be looking into purchasing the Suzuki 2.5 HP. The only problem is that there are no Suzuki outboard motor dealerships anywhere near me. If I run into similar or other issues with the Suzuki, I want to have some recourse, which makes purchasing from an online dealer a bit daunting. I'm wondering how Suzuki or other outboard models prevent water from entering into their cowls.
The use of these small outboard motors, designed mostly for light duty boat tender use, presents an extreme duty usage on the TI where it must be impervious to severe splashing in all kinds of conditions, and able to run at high rpms for hours on end. Few of these motors will have the "right stuff". The Tohatsu certainly did not.