High-Pressure Fuel Pump - Mercury V6 175 Diagnostic Manual

High‑Pressure Fuel Pump
When the ignition key is turned ON, the high‑pressure fuel pump is active for approximately three seconds. After the first three
seconds, the high‑pressure fuel pump will not run until the PCM recognizes engine RPM. The PCM does not have the logic to
detect the high‑pressure fuel pump operation. In the event of a high‑pressure fuel pump failure, no fault will be generated and
the engine will not run. The high‑pressure fuel pump sends the fuel through a 20 micron fuel filter and into the bottom of the fuel
rail. There is an internal overpressure relief of 689.5 kPa (100 psi) for the high‑pressure pump. The fuel rail pressure is
controlled by a fuel pressure regulator. The fuel pressure dumped by the fuel pressure regulator passes through a fuel cooler.
Passing the excessive fuel through the fuel cooler prevents the high‑pressure fuel pump from overheating.
90-8M0146617 eng JULY 2018
47839
© 2018 Mercury Marine
Fuel System
Page 7A-9