Our Dinghy is like our car. Worse, without our dinghy we can’t even walk somewhere as we are trapped on our boat. Without a proper running dinghy our quality of life quickly drops and life becomes super frusterating. So you can imagine how frusterated I got when our dinghy started acting up. Then shortly after our dinghy started acting up, Last Tango’s began to behave exactly the same. Since our motors are identicle except the stickers (mine is badged Tohatsu and his is Mercury), I guessed we had picked up some bad fuel somewhere.
I was actually surprised when it started acting up as I had not been treating my dinghy motor very well and never had a problem. I was doing this to partly prove a point and to see if I could prove myself wrong. You see, when I bought a 4 stroke motor I had many people tell me I should have waited until Bahamas and bought a 2 stroke (2 strokes are banned in the USA). They said 4 strokes were finicky and too intolerant to poor fuel quality. With my background in small motors I didn’t beleive a word of it. So for better or worse I set out to see if this was true (this cruising life keeps proving me wrong).
The first “no-no” I did was run our motor on regular E10 fuel from the pump. Thats right for the first 2 months of its life our motor was fed regular automobile gasoline from non marine pumps. However, I always made sure to purchase from a high volume fuel station where I knew the fuel was fresh. We even left Florida with 40 liters of “automobile” fuel that we continued to burn all the way to the Dominican Republic. Our engine ran fantastic and never gave any issues.
The second “no-no” I did was to leave fuel in the carb for extended periods of time. There were a couple of weeks where our dinghy motor wasn’t started at all. I never ran the carb dry or drained any fuel out and she still started right up after a couple of pulls. This even includes the 2 weeks we stayed in a marina and didn’t start the dink once!
Finally I didn’t close the vent, ever. Rain, shine, harbor or passage I left the vent open. Now this is the one I though would bite me for sure. If water was going to get in the fuel, I was sure this would be the path in. Nope, for over 4 months our motor gave use zero issues.
So I was super surprised when I started having idling issues while in St. Thomas USVI. They were intermittent and would clear up for a day or two (looking back they didn’t completely clear, the motor always idled rough when it did idle). Shortly after our motor started doing this, Mike’s motor started doing the exact same thing. After a couple of conversations we figured out that we both got gasoline in Ponce, Puerto Rico and had just started using it. Sigh, we had obviosly got fouled fuel as both motors doing the same thing while using fuel from the same source was too big a coincidence. So I became adept at feathering the throttle and shifting into gear at exactly the right time and then feathering the throttle again to get moving. Problem sovled…. LOL.. No.. You may also remember I had an issue where the motor oil got filled with gasoline. Those 2 issues are related as fouled fuel can cause the carburetor float to stick open and allow gasoline to flood through carb. The new EPA approved fuel tanks make this issue worse as these tanks are not allowed to vent back to atmosphere. So a sun heated fuel tank will build pressure and if the float is stuck push fuel into the motor, if you are unfortunate enough to have the intake valve open, then it can fill the crank case with fuel (as happened in our case). So, I put the dinghy motor on my list.
Today was the day I got to that item. The hardest part of the job was to hoist the dinghy in a way that would allow me to work on the motor with minimal risk of donating an item to Davey Jones. Once the carb was off the motor, I had it tore down and parts soaking in acetone within 10 min. It was very clear what the problem was. There was small brown sand like particles in the float bowl. Now you may ask how those particles get past the filter (actually 2 filters on our motor). Beleive it or not, those particles are actually oxidised gasoline and were liquid when they passed through the filter, then oxidised later and became solids (plugging the jets). In the past while fixing generators I actually had carbs come in that looked like they had been filled with sawdust. Badly oxidised gasoline will turn into a brown semi-hard dust, but that usually only happens when water is present. The gasoline we got in Ponce most likely was contaiminated with water. It probably wasn’t enough water for a big boat with a big motor to notice, but was a problem for our small EPA approved carbs. Anyway.. After soaking, scrubbing and poking (jets) the offending carb was reassembled and reinstalled. 5 pumps of the fuel bulb and 2 pulls on the cord had the motor purring like brand new.
Now.. I can actually here the skeptics out there shaking thier heads. Well to confirm my suspicions, I called Mike to bring his dinghy over as it still had the idle problem. His carb had the exact same small brown contaiminants. Same fix, same 5 pumps of the fuel bulb, same 2 pulls… Runs like brand new! Now the downside of owning a 4 stroke motor is that it would have taken forever to burn up the Ponce gasoline in our motors. Since that gasoline was now banned in our motors we needed to find somewhere to get rid of it. Strangly enough, it seems to have no affect on my Honda generator. So we are now using that fouled gasoline to make water with. I sure hope I’m not cursing myself in a month because I have to fix that carb! We will see.