Re: Lots of gas in Oil-Nissan 2stroke nsf8/9.8
Elvin is right on the mark.
The NSF9.8A3 could burst a fuel pump diaphragm if the fuel tank has the vent closed and sits in the blazing sun -- causing a lot of pressure.
Often, fuel dilution of the oil is from idling a lot when very cold, not breaking in the motor properly, overfilling the crankcase, running oil that is too heavy, over choking, or a stuck carb float dumping extra gas. Or any combination of these things.
Most prudent thing to do is run the carb out of fuel after each use.
Use NMMA FC-W rated 10w-30 oil, and don't overfill, not even a drop. Always check the dipstick when changing oil -- some oil typically gets left in the motor, so just dumping in "about" 3/4 of a quart is a great way to overfill the crankcase. During the first 10-20 hours of break-in use, half way on the dipstick is plenty.
The Factory service manual, Covers Tohatsu/Nissan 8A & 9.8A 4-stroke models Part # 003-21056-0 List Price (MSRP): $26.52, available from any Tohatsu/Nissan dealer is the best for these motors, though some of the Japanese translation is less than perfect.
If the carb needs cleaning, it must be completely disassembled, and submerged in a good carb dip such as Tyme, for 4 hours, then rinse it out and reassemble it, checking float height (which is usually perfect on these plastic floats).
If you do diagnose a bad fuel pump, a new one is available: 3H6040004M FUEL PUMP, 4/5/6/8/9.8 4-STR ONLY $55.70.
Modern gas starts spoiling within 30 days, especially in a naturally-vented tank. Years ago, we used to top up all tanks for winter storage, but now we prefer to completely empty them. A good stabilizer, such as K-100, helps, if used in the proper ratio, and added religiously when the tank is filled, but adding stabilizer to old fuel doesn't do as much good. If the fuel should become phase-separated (where the alcohol/water drops out), there is no reasonable way to "put the genie back in the bottle", and the whole load of gas is then junk. When winterizing in the fall, the gas from the boat can be used up in the car or truck, even pre-mixed 2-stroke gas. Dumping a couple of gallons of 50:1 gas in with 10 or 20 gallons in the car tank does not hurt a thing, and you at least get to use up the old gas before it spoils.
