This document provides installation instructions for a Weichai WP04GNA engine certified by the EPA for non-emergency applications. It includes details on installing emission control components like the closed crankcase ventilation system, oxygen sensors, catalytic converter and more. The engine control system uses a 4G ECM to operate at the stoichiometric air-fuel ratio and control emissions via a three-way catalytic converter. It can be configured to run on natural gas, propane or both fuels.