Maddox Deluxe Fuel Injection Service Kit (MD39-1). Maddox MD39-1 Fuel Injection Tester Gauge & Hose Assembly. Up for sale is aMaddox Deluxe Fuel Injection Service Kit (Model MD39-1). This is a comprehensive, professional-grade diagnostic suite designed for testing fuel pump pressure, identifying faulty regulators, leaking injectors, and clogged fuel filters.
