A fuel injector pressure tester is an instrument that can perform fuel pressure tests on cars and trucks equipped with electronic fuel injection systems. A fuel injection pressure tester helps identify and diagnose low fuel pressure, a faulty fuel pressure regulator, leaking injectors, fuel leaks, and clogged fuel filters. Most testers come as a kit containing a pressure gauge (sometimes there are two, for accurate high pressure and low pressure readings), and a selection of adaptors and fittings to cover the majority of modern fuel injection systems.

On most vehicles, two basic tests are carried out when checking fuel system pressure: "key on engine off" (engine not running) test and "key on engine on" (engine running) test. Unless otherwise noted by the vehicle's manufacturer, engine running tests are performed with the engine at idle.