Originally Posted by
Pomoxis
Here is a few "last tips of the night".
I wouldn't put Sta-Bil in my outboard fuel if you handed it to me along with a $50 bill. It does exactly what it says on the can. So I can't blame them for lying. It will prevent the formation of deposits and will also prevent the evaporation of the fuel. The problem is that fuel must evaporate to burn. Sta-Bil treated fuel may make it impossible to start your motor. You may have to drain it and flush it with new gas, including the carb, to get her started.
I actually heard this from a retired EXXON chemical engineer about 25 years ago. Unfortunately, it was about 15 years ago that I had rebuilt a "classic" 1970 9hp McCullough outboard. When I got done with it, that thing ran so well you could literally get it started by gently turning the flywheel by hand. After a week of rest it would start with the most gentle rope pull, and would idle instantly, good enough to troll for lakers all day. I used to do that for people who would not believe me. It was January and I was ready to put the thing to sleep for about 3 months, so I did what an associate recommended. I used some Sta-Bil. A motor 'that good' had to be treated just right, I thought! About two days later, another friend came over and I decided to show him the "miracle motor". It wouldn't start no matter what I did. It would not even fire once. I never lived that down, except to myself. I have been servicing all kinds of motors for my whole life, and I knew that simple thing inside / out! I also loved it. The only thing that got it started was to completely flush the carb and the entire fuel system. Man, was I pissed, but not at the motor, I was pissed at the Sta-Bil. I am also a scientist. I took some gas with Sta-Bil in it and poured a little in a cap and threw a match at it. It would not burn! I am not kidding. I have owned and serviced a large number of gasoline engines. I have never used that Sta-Bil crap in any of them ever, except for the McCullough. I have also never had a fuel related starting problem with any of them ever, 1, 2, 4, 6, or 8 cylinder, or any 2 cycle, even the ones that sat still for YEARS with gas in them!!!! All of a sudden I had a flashback to what Mr. EXXON said. "Modern gasoline is totally different from the old stuff. You don't need to add anything to it".
Apparently you don't, with regards to preservation. I have not seen "gumming" in a carb on a 2 or 4 cycle engine in at least 25 years.
However, it is possible to get enough 'water' into your gas to cause a problem. In that case use 'Isopropyl Alcohol' gas dry. Follow the directions and be prepared to do fuel draining in severe cases. Run the wet stuff in your car. 4 cycles are much more tolerant than 2 cycles.
It is also possible to get 'particles' in a carb.
That happened to the Johnson outboard I use every week, almost all year. The fuel was filtered up to 'before the fuel pump'. The fuel pump was actually releasing particles from its gasket small enough to get through the float valve, but big enough to clog the main jet. Removal of the particles fixed it, both times it happened. I'm still looking for an in-line filter, for 5/32 line, small enough to fit there, after the pump, before the carb.
Conclusions:
It is probably wise to use a "water separating fuel filter", even on a seemingly small outboard rig, when you are going beyond a few miles from safety. They change out just like oil filters. They are used all the time on bigger saltwater rigs. Nobody wants to go out there with the chance of that happening. I don't have any experience with using alcohol on a rig with that kind of filter, but it works on rigs without that filter if you are willing to spend time running the alcohol through. And I don't want 30 minutes of Crappie fishing time taken from me on any Crappie fishing trip. Check your fuel system for water leaks at the "filler cap" and the "tank air vents". Remember, just because you didn't see water getting in, doesn't mean it didn't get in. A small amount of Isopropyl on a regular basis may prevent any "water in the fuel" surprises. Also, remember that water is not necessarily death. I ran a water-injected, carbureted, Chevy smallblock car on the street for 7 years. Water injection can clean and reduce octane requirements. But, liquid water in liquid gas can be out of control, a no-start.
Carbs are great, but sometimes you have to treat them just like women, look for the TINY little things that are annoying. But it is easy, when you know how.
Fuel injection is another animal...but most of the same things are true.
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...buddy of mine turned me on to Sta-bil, so I tried it..that was 15 years ago and I have'nt had to pull a carb or do any clean-out since..... :p ....usually just have to pull cord 2-3 times and they fire right up...I leave gas in em year round with no problems, just fired up my leaf-blower after sitting for 8 months...I worked as a mechanic for the last 10 years until I hurt my neck and all the guys/gals i worked with swear by Sta-bil, I also have a friend who runs a outboard repair business and both he and all of his customers use Sta-bil with no ill effects...... :rolleyes: 
