An Emission Comparison Between a Carburetor and an Electronic Fuel Injection System for Utility Engines

An Electronic Fuel Injection system has been developed for utility engines which will reduce exhaust emissions and give greater control of the Air/Fuel ratio compared to the standard carburetor. Standard automotive components were used when possible.

The Electronic Fuel Injection system is a port fuel injected design using a bottom feed fuel injector which sprays directly on the intake valve. The engine speed/position, throttle position, air intake temperature and cylinder head temperature are measured and fed into the Electronic Control Unit. Look-up tables are used to determine the injection duration time during starting, warm-up, acceleration and normal operating conditions. Normal operating conditions are conditions the engine would encounter during actual use such as idle to governored rpm, no-load to full load, ambient temperature ranges from -40°C to 55°C, and any combination of the above. Corrections for engine overheating are also made, but not for a restricted air filter element. An electric fuel pump and mechanical pressure regulator were used to supply and control the fuel pressure to the fuel injector.