The present invention is a system and method for adapting and modifying an existing mono-fuel delivery system for an internal combustion engine to run as a bi-fuel system by reusing and repurposing OEM components of the mono-fuel system. The bi-fuel system makes use of an integration plate that may be mounted to the system fuel filter in substantially the same location as the fuel filter is mounted in the mono-fuel configuration. The integration plate also may deliver either fuel types into the existing engine fuel intake port thus the system does not require the creation of a secondary fuel intake port for the secondary fuel. The integration plate may also be situated such that it minimizes the space it must use within the engine compat anent and it may use the preexisting engine mounting points designed for the fuel filter in the mono-fuel system.