Home » Tony’s Tips » Articles » Measuring Fuel Pressure on a Cummins 6CTA 8.3Measuring Fuel Pressure on a Cummins 6CTA 8.3 Measuring fuel pressure on a Cummins 6CTA 8.3 taken from the on-engine fuel filter head. 20 PSI is measured at engine idle vs. 40 PSI at or around 2000 RPM