Abstract
Most of the motorbikes in developing countries use carburetor for the metering of fuel with air. However, carbureted vehicles have many drawbacks such as higher fuel consumption, cold start problem, and many hazardous emissions. Electronic Fuel Injection (EFI) is a sophisticated and effective fuel delivery system that is developed to replace carburetor in order to increase fuel efficiency and reduce emissions and it is also a low cost alternative in an effort to reduce fuel costs and air pollution. In this paper, a comprehensive study was performed by replacing carbureted system with a closed-loop EFI system for small 70 cm(3) 4-stroke gasoline engine and test results were extracted by comparing both systems in terms of fuel consumption and its drivability. The results show that EFI system improves average fuel economy of 13% on most of its speed ranges and it also offers significant fuel saving of 16.4% on loaded condition relative to otherwise equivalent, carbureted baseline vehicles. The reasons for better fuel efficiency are due to the determination of correct fuel quantity for different engine operating conditions by using pulse-width correction factors and by engine maps optimization with respect to engine speed and load. Other benefits related to this system, are improved cold start and drivability.