Monitors the tach signal - as long as there is a tach signal present, the pump is allowed to operate. If the engine stops, so does the fuel pump. Works with both inductive (stock) and square-wave (aftermarket) tach signals. For vehicles without a tach, connect to the negative side of the coil. Turns on an electric fuel pump for 3 seconds on initial key-on. This primes the fuel system and tops off the carburetor's fuel bowls. Controls an electric fuel pump when a classic car or truck is upgraded from a mechanical fuel pump. Includes an internal self-resetting 7 amp fuse and 15 feet of 16 gauge wire to connect the fuel pump. Higher amperage pumps can be controlled by adding an external relay. For 12V vehicles. 2 by 1.5 by 1 inches. Fully potted. Made in USA Designed to safely control an electric fuel pump when a classic vehicle is upgraded from a mechanical fuel pump to an electric fuel pump. Powers the pump for three seconds on initial power-on to fill the carburetor bowls. After those first three seconds, the pump will only run if there is a tach signal. If the tach signal stops, the pump shuts off. Includes an internal 7A self-resetting fuse, 15 feet of 16 gauge wire, and the necessary hardware for most installations.