Regulating Fuel Flow
By: Kent Lester
It just makes sense that if you have thousands of computations taking place every second and mechanical “squirt guns” (injectors) to get the fuel into the cylinders, there could be a problem with fuel delivery.
This challenge is handled by using extremely high pressure in the fuel system and very sophisticated injector nozzles to open and close at the same rapid level the ECU is calculating.
For this reason, electronic fuel injection systems use a very powerful pump, usually located inside the gas tank, to get the pressure high enough in the fuel rail for the nozzle to respond as quickly as possible.
The fuel rail is merely a distribution reservoir for gasoline where the highly pressurized fuel can be ready for instantaneous delivery to the nozzles.
EFI throttle bodies are located the same place a carburetor would be situated and from the outside actually look pretty similar. There’s one massive difference between a carburetor and a throttle body. No fuel flows through an EFI throttle body – only air.
Air flow is regulated by a flapper style butterfly valve monitored by the throttle position sensor (TPS). Gasoline is introduced to the cylinders via the injectors only and, in port style injection systems, the most common type with snowmobiles, the injector nozzles are located between the throttle body and the engine, either on the intake manifold or the cylinder head.
The idea is to get the nozzles as close to the intake valves as possible.