The Backside Auto - Injection System (BAIS) is designed to allow gas to be injected into the packerless production tubing/casing annulus intermittently without having to pull the tubing and install gas-lift mandrels and valves. This is accomplished by using a single portable wellhead compressor to collect gas from the tubing and simultaneously compress the gas down the casing-tubing annulus. The control of gas flow is directed by pressure activated motor valves. As the gas enters the bottom of the tubing, the gas-liquid ratio (GLR) is increased sufficiently to unload the wellbore liquids to the surface. Once unloaded, the gas flow is directed to sales until further loading is detected by the BAIS. This system is designed to provide liquid unloading and economic production enhancement to marginal gas wells.