This tool is designed to prime the fuel system on Caterpillar C-7 (and 3126) engines from the fuel tank to the fuel filter.  As many technicians have found this job can be very difficult if the engine doesn’t have a hand primer.  To simplify this operation & reduce time needed we offer a priming tool that consists of the special quick coupling & hose.  You only need to supply vacuum on the end of the hose and wait for the fuel to be drawn from the tank through the fuel filter