Fuel Injection
Fuel Pressure Regulator
A fuel pressure regulator holds fuel pressure at the level your injectors need and returns or blocks the excess. We carry 41 regulators from $20 to $381 for engines from 1985-2014, from Standard Motor Products, Delphi and AC Delco, with the Chevrolet S10 and Corvette among the most listed fits.
Shop fuel pressure regulator by vehicle
What the regulator does
Injectors need steady pressure to deliver the right amount of fuel. On return style systems, the regulator uses a spring and diaphragm to send extra fuel back to the tank. Many regulators also have a vacuum line so pressure tracks engine load.
Listed pressures in this category range from low pressure units rated 9-20 PSI, typical of throttle body injection, up to 65 PSI units. Using the wrong rating will upset fueling.
Symptoms of a bad regulator
A torn diaphragm can let fuel into the vacuum line, so check that hose for wet fuel. Other signs include black smoke, a fuel smell, poor economy, hard hot starts, a rough idle, or low power from pressure that is too low.
A fuel pressure gauge is the best way to confirm the fault. Compare the reading at idle, with the vacuum line removed, and after shutdown against the factory specification for your engine.
Choosing the right part
Check whether your engine uses a regulator on the fuel rail, inside the throttle body, or in the tank as part of a returnless system. Match the pressure rating and the port layout. Some kits include the diaphragm assembly, gasket, foam rings and alignment rods, which suits GM throttle body units.
Adjustable regulators appear here for performance builds. For stock repair, a fixed regulator matched to your engine is the usual choice. Relieve fuel pressure before you remove the old part.
Fuel Pressure Regulator questions
How do I test a fuel pressure regulator?
Connect a fuel pressure gauge to the test port, then compare pressure at idle and with the vacuum hose pulled off. Pressure should rise with the hose off. Fuel in the vacuum hose points to a leaking diaphragm.
Can a bad fuel pressure regulator cause black smoke?
Yes. If the regulator leaks or sticks closed, the engine can run rich, which may cause black smoke, fuel smell and fouled spark plugs. A gauge test confirms whether pressure is too high.
Do I need an adjustable fuel pressure regulator?
Not for a stock engine. Adjustable regulators are meant for modified engines that need a different base pressure. For a standard repair, choose the regulator listed for your engine.