To use this K-Tuned fuel rail fitting, first make sure you have a K-Tuned K-Series Fuel Rail. If the fitting is not already on the rail, you may need to remove the fuel rail to install the fuel line due to the size of the fitting. Connect the fuel line to the -6AN port for either fuel feed or return. Then, attach your gauge to the 1/8 NPT port. The gauge is sold separately, so make sure to get one that suits your needs. As for maintenance, regularly check the o - rings on the fitting. These o - rings are important as they prevent fuel leaks caused by engine vibration. If you notice any signs of wear or damage on the o - rings, replace them immediately. Also, keep an eye on the fuel line for any signs of damage or blockage. If you experience any issues, consult a professional mechanic.