RepairPal Certified shops can diagnose and repair your 1999 GMC C1500. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
The fuel pressure spec for 5.0L and 5.7L V8 engines is 60-66psi with pump running and engine off, 55-60psi with key on after pump turns off. Fuel pressure should hold steady after turning the key off.