Wheels: Don H. writes by email: “I appreciated your recent article on the use of proper fuels in new cars. Do you have much experience with small engines, such as Tecumseh and Briggs & Stratton that are used on walk-behind lawn mowers? My last two mowers (one of each engine) no longer have manual chokes and specify the use of 87 octane gasoline.
With both mowers, I have had great problems starting them (10 to 20 pulls) on their supposed “guaranteed start with one or two pulls” of the starter cord.
Returning the mowers to the point of purchase dealers for correction has resulted in only handling fees, disruption and delay in my mowing cycle. The dealer’s response to the supposed cause for not promptly starting is the use of regular (87 octane) gas. I always have used new, fresh 87 octane gas, but have been told instead to only use premium gas because it has better starting qualities.
Previous to these mowers, I never had any trouble starting mowers by pushing the manual bulb chokes when using regular gas. Is there anything you can suggest to improve starting without the purchase of premium gas or additives? Calls to Tecumseh and Briggs & Stratton have resulted in nothing of use. Thanks for all your useful auto articles and my hope for the small engine cure.”
Halderman: You are correct that there is a lot of misunderstanding out there. One of the reasons that many lawn mower shops recommend the use of premium gas is that mowers often backfire when being shut off and this is reduced, but not cured by the use of premium.
Another issue that may or may not be your issue is that gasoline has a “shelf life” of three months (90 days). This means that for the best performance of gasoline, it should be used within three months of purchase.
What happens is that the “light ends” (most volatile) parts of the fuel tend to evaporate which would make the mower harder to start. If you are purchasing five gallons of fuel at a time, consider using a smaller, 2-gallon gas container to help make sure that the gasoline is fresh.
I suggest that you use a gasoline stabilizer in all of the gas being used for small equipment.