Why Can't the Pull-Start Gasoline Engine Be Started?
3 Answers
Pull-start gasoline engines may fail to start due to impure gasoline or the presence of water and other impurities in the fuel tank. Below is relevant information about gasoline engines: 1. Composition: A gasoline engine is an internal combustion engine that uses gasoline as fuel and ignites via an electric spark. It typically adopts a reciprocating piston structure, consisting of the engine block, crankshaft-connecting rod mechanism, valve train system, fuel supply system, lubrication system, and ignition system. 2. Advantages: Gasoline engines are lightweight, have lower manufacturing costs, produce less noise, and offer better cold-start performance. Compared to diesel engines, gasoline engines are lighter, cheaper to manufacture, quieter, and perform better in cold starts. However, they have lower thermal efficiency and higher fuel consumption rates.
This situation often happens to gardening novices like me, and there are usually several common reasons. If a new machine or one with freshly changed oil won't start, it might be due to excessive oil causing high internal viscous resistance—just loosen the drain screw slightly to let some out. For older machines used for several years with a pull cord stiff as an iron rod, it's likely due to carbon buildup on the piston rings or stuck valves; you'll need to remove the spark plug and spray some rust remover into the cylinder. Additionally, if the cord snaps back painfully when pulled, it indicates the flywheel teeth or spring is damaged and needs replacement. Most importantly, first check if the choke is in the correct position—starting a cold engine without closing the choke will definitely make it immovable, and this is the most easily overlooked issue.
I've seen too many cases of pull cord breakage, most of which are caused by internal structural issues. Gasoline deterioration and gum formation in the carburetor float chamber can block the fuel passage, completely locking up the engine; a severely dust-clogged air filter preventing air intake can also make the cylinder unable to compress. More troublesome is when the crankcase oil emulsifies and deteriorates into sludge, or when the connecting rod bearings wear out and seize. It's recommended to first remove the spark plug to check cylinder compression: if the pull cord feels light with no resistance, it's likely due to valve leakage; if it's so heavy that it can't be pulled at all, the piston rings might be stuck to the cylinder wall.
