There are two types of gasoline powered scooter: the carbureted indirect injection engine and the injector direct injection engine. In the first case, gasoline is mixed with air outside the engine in a carburetor. In the second case, gasoline is mixed with air directly in the combustion chamber. The gasoline circuit goes from the tank to the engine. Throughout this circuit, gasoline passes through the fuel filter, carburetor or injector and ends up in the cylinder. The arrival of gasoline in the cylinder is characterized by the humidification of the spark plug electrode by gasoline when the starter is actuated without going so far as to start the engine. However, it turns out that gasoline does not reach the spark plug and the spark plug is dry when the starter is turned. We will thus understand where in the fuel supply circuit the gasoline could be blocked.
Scooters - general information
Here is an article that serves as a guide and helps you choose your scooter better before purchasing. For this, we give you the details on the characteristics and the different types of scooter.
The prerequisite: dosage of the air / gasoline mixture
The carbureted engine is characteristic of an indirect injection engine. This means that the air / gasoline mixture does not take place in the engine, but outside the engine. This external mixture is provided by the carburetor, the function of which is to correctly dose the air / gasoline mixture. If this configuration is not done correctly, it may cause different breakdowns or malfunctions.
As for direct injection, the air / fuel mixture takes place directly in the combustion chamber. This function is performed by the injector, the objective of which is to inject gasoline in the form of gas into the engine. The metering of the volume of air required for a given quantity of gasoline is managed by a computer called the calculator. In all cases and regardless of the technologies used, carburetor or injector, the ideal mixture ratio is around 15 grams of air for 1 gram of gasoline.
Check the gasoline supply circuit that does not reach the spark plug
We have seen what are the mechanical parts that mix air with gasoline, but also how the air / gasoline dosage works. These notions are essential for us to be able to understand why gasoline does not reach the candle. First, the gasoline circuit goes from the tank. The fuel then passes through flexible pipes or hoses to pass through a fuel filter where the solid particles are retained. Then the gasoline is routed to a gasoline tap before reaching the carburetor or injector. From there it is mixed with gasoline and then vaporized as a gas in the combustion chamber of the cylinder. When compressed by the piston, the sparks of very high voltage current supplied by the spark plug electrode will cause the fuel to explode. Until then, the system is functioning normally. The risks of a poorly dosed mixture
If the quantity of air is found in excess with respect to the volume of the gasoline then the air / gasoline mixture is qualified as poor (poor in gasoline). In this case, the amount of gasoline that will reach the spark plug may be minimal or nil. We will have the impression that gasoline does not reach the candle. On the contrary, if there is little air compared to the normal rate then the mixture is said to be rich, rich in gasoline. In the latter case, the spark plug may be too wet to be able to properly produce a spark.
Gasoline that does not reach the spark plug: Replace the fuel filter
When gasoline no longer passes through the fuel filter, it is high time to replace it. However, it is recommended to change the fuel filter at a frequency communicated by the scooter user manual provided by the seller or by the manufacturer. When the gasoline is blocked by clots of particles in the piping, it is enough just to clean the whole circuit of the piping to remove the large particles which clog it. To do this, it suffices to inject high pressure air into the pipes to unblock the circuit. In this case, the entire fuel system will have to be replaced. We can say that we can also find other malfunctions or problems with fuel-related components.
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Check the carburetor or injector if gasoline does not reach the spark plug
If after replacing the fuel filter and then cleaning or replacing the piping, the fuel still does not reach the spark plug then the carburetor or the injector will have to be blamed. The carburetor is a mechanical organ where gasoline and air intersect and mix. This part is made up of small and large orifices which circulate gasoline and air. These orifices are found to be clogged with particles preventing fuel from passing through the carburetor properly. In this case, it is desirable to disassemble all the detachable parts of the carburetor and clean them with gasoline. As regards the pipes, cleaning will be done by air injected at high pressure. Equip yourself with an air compressor to achieve this. Also check that the needle which is the carburetor valve lets the gasoline through when it is not under pressure. In the case of an injector system, the easiest way is to tare the injector to diagnose if gasoline is being ejected at the desired pressure.
