I've seen it a few times too - in either/both an MS290 and a 036 (Pretty sure the MS290, likely the 036 too).
We had at least ten members in this thread say they have seen it. I have seen it twice but just in this saw. Mind you it is the only one I have with a metal fuel tank. so is there a fix? is there a concern long term to the saw? etc.
Fuel boiling in the tank is nothing new at all, the older saws simply vented into the atmosphere and it was not an issue with them. When the manufacturers were forced to start using sealed fuel tanks then a newer design of vent prevented the fuel vapor from escaping into the atmosphere, the fuel tanks were still metal and often just a part of the saw, they were not separated and this caused some fuel delivery problems. Manufacturers went to the separate fuel tank designs, most started using plastic tanks and this helped a lot but on hot days with the engine contributing additional heat the fuel still boils, the tanks are now all sealed with the vent only allowing air to enter a tank, no fuel or vapor to escape into the atmosphere. Tanks will pressurize easily, the carbs are designed to work with this pressure and there is nothing that will really stop this. It has already been mentioned about the different gasoline mixtures supplied by the refineries for winter, its been noted that some mixes boil more easily and that certain grades will be a little more resistant to boiling than others. I have used all grades supplied for my area and they all boil when the temp rises, there really is nothing that can be done to stop this with regular pump gasoline. When the tank pressurizes the fuel is actually force fed to the carb , the spring under the metering lever is designed with a pop off pressure that prevents too much fuel from entering the fuel bowl part of the carb and flooding out the engine so the engine will run normally with the fuel boiling in the tank. By leaving the tank cap on the fuel will boil less as the pressure inside the tank rises but care must be taken when removing the cap as the sudden release of the built up pressure will cause spraying of fuel mix.
it's new gas. I bought it at a Shell station that sells 93 octane non ethanol fuel. Could the non ethanol be a contributing factor?
Jerry,
so on these older saws, it is to be expected? and it just goes with the design? I postd some pics in my second post that show a little fuel dribbling under the clutch cover, is this the saw's attempt to regulate the boiling and keep te saw from flooding?
thanks
Jerry,
so on these older saws, it is to be expected? and it just goes with the design? I postd some pics in my second post that show a little fuel dribbling under the clutch cover, is this the saw's attempt to regulate the boiling and keep te saw from flooding?
thanks
The $109.00 pm700 arrived today. Its very oily grimy. The fuel tank is missing the 2 bolts to hold it on. One at rear carb and in oil tank. The 2 bolts under the carb were loose. The coil was very loose rubbing the flywheel. Has the wrong spark plug in it. But, it has great compression and no scoring on the piston or cylinder!! I can replace bolts. The clutch cover though broken at muffler is usable. I have one off of a sp81 i can use if it makes it look better. But i think ill have a great runner once i clean it and put it back together. Ill post once its clean and running. Jethro, its got a sdc 44a carb on it.
so my buddy is going through this on his XL-925 now, it runs great...until you shut it off, then open the cap and see the boiling and saw will not restart until cooled...
That is quite a range!!Gasoline can start to boil at 95F - 200F
Enter your email address to join: