Test for fuel line pressure and vacuum leaks and check for leaky valves, timing, fuel pump vacuum and pressure and gas line leakage. Tester is equipped with an easy-to-read gauge with a 3_ hose and a vacuum hose adapter fitting. Gauge measures vacuum from 0 to 28_ Hg in 1_ increments (0 to 700mm Hg in 50mm increments). It also measures pressure from 0 to 15 psi in 1/2 psi increments (0 to 1 kg/cm2 in 0.1 kg/cm2 increments). Gauge diameter 2 11/16_. Caution: Not for use on fuel injected vehicles.