Utility spark ignition gasoline engines are deployed worldwide for a variety of functions including transportation, power generation, and fluid movement. These engines are typically air-cooled and employ cost-effective carburetors and fixed angle spark ignition systems. Although utility engines are generally operated on the same gasolines available for highway vehicles, there are remote applications where gasoline formulations may be substantially degraded. Until recently, two and four stroke utility engines have not been a focal point for performance enhancement or pollution control technology. However, the growing awareness of small engine pollution, as well as legislated federal and state requirements, presents many engineering challenges. In this paper, an analytical and empirical model is presented to describe the behavior of internal combustion spark ignition utility engines. The nonlinear engine model will support the design of model-based and intelligent control algorithms prior to dynamometer testing. An electronic control system architecture is introduced using a multi-purpose programmable engine controller which is capable of regulating fuel injection and electronic spark ignition subsystems.