Fuel injectors are controlled by the onboard computer to meter and atomize the correct amount of fuel entering each cylinder in the case of the PFI and the correct amount of fuel entering the intake manifold in the case of the TBI, under all operating conditions. Symptoms of failure include poor starting, engine surging, check engine light, and or no start conditions. Recommended service should be performed every 25,000 - 35,000 miles and consists of cleaning or replacing with new injectors.Walker Products began supplying the fuel system needs of the automotive industry in 1946. Today Walker is one of the largest, privately owned manufacturers of fuel system components and engine sensors, and has served the needs of the worldwide automotive aftermarket. We are committed to supplying products manufactured to meet or exceed OEM standards and specifications. This effort is backed by our own manufacturing, product management and engineering staff to ensure it is maintained and accurate in the production of quality parts, vehicle applications, instruction sheets and technical support. Our products include Carburetor and Fuel Injection Repair Kits, Oxygen Sensors and other Engine Management products such as Throttle Position Sensors, Cam and Crankshaft Sensors, Fuel Injectors, Spark Plug Wires and Gaskets. As an ISO 9001:2008/TS16949 certified company, we are committed to supplying the highest quality products.