SYSTEM FOR DETECTING FAILURE OF FUEL PRESSURE SENSOR

摘要

A system for detecting failure of a fuel pressure sensor in an internal combustion engine, including an injector (32) provided at an intake system of th e engine downstream of a throttle valve (38), a fuel supply passage (16) connected to a f uel supply source (fuel tank 12) for supplying fuel to the injector (32), pressure regulato r (28) provided in the fuel supply passage (16) and operating to maintain a difference between the fuel pressure (PF2A) and the manifold absolute pressure at a constant value, a f uel pressure sensor (PF2 sensor 54) for detecting the fuel pressure (PF2A) in the fuel supply passage (16) downstream of the pressure regulator, and a manifold absolute pressure sens or (62) for detecting the manifold absolute pressure (PBA) downstream of the throttle va lve (38). In the system, an index indicative of a ratio (.DELTA.PF2A) of the fuel pressure (PF2A) fluctuation relative to the manifold absolute pressure (PBA) fluctuation is comp ared to reference values (#PF2L, #PF2H) which define a range. Sensor failure is discrimi nated when the index (.DELTA.PF2A) is found to have remained outside of the range for a predetermined maximum time (tmP2STK). The system enables rapid and accurate detection of fuel pressure sensor abnormality (failure).