what is the correct fuel psi for a 1999 GMC Sierra 4.8L?

[Knuckle Deep]

Bought an adjustable fuel pressure regulator and looking for the correct PSI. Thanks.

 

[Molson02536]

Bought an adjustable fuel pressure regulator and looking for the correct PSI. Thanks.

When the ignition switch is ON and the fuel pump is running, the fuel pressure indicated by the fuel pressure gauge should read 379-427 kPa (55-62 psi)

A rich condition may result from the fuel pressure being above 427 kPa (62 psi) This condition may cause DTC P0132, DTC P0152, DTC P0172 or DTC P0175 to set. Drive ability conditions associated with rich conditions can include hard starting followed by black smoke and a strong sulfur smell in the exhaust.

A lean condition may result from the fuel pressure being below 379 kPa (55 psi), and this condition may cause DTC P0131, DTC P0151, DTC P0171, or DTC P0174 to set. Drive ability conditions associated with lean conditions can include hard starting, hesitation, poor drive ability, lack of power, surging, and misfiring.

Good luck and hope this helps you set your FPR.