Cummins ISB CM550 (1990-94) Fault Code: 517 PID: 252 SPN: FMI: Fuel Pump Valve Feedback Error

Circuit Description
A mechanically stuck fuel control valve has been detected by the pump controller.

Component Location
The fuel pump is located on the backside of the gear housing.

Shop Talk
This fault is typically set when a fuel pump beginning of injection point error (bit 10) is
recognized at engine speeds of more than 700 rpm and commanded fueling of more than 20
mm³ for two seconds at a battery voltage of 9 VDC. In most instances, Fault Code 517 will occur in conjunction with Fault Code 363. The same diagnostic steps can be applied. The fault code can also be triggered by electrical noise,
voltage feedback on ground loop, or high fuel return line restriction.