Fuel system for internal combustion engine

In a fuel system for a multicylinder compression ignition engine, said fuel system comprising

• a plurality of fuel injectors, one for each cylinder of said engine, said fuel injectors being adapted to inject fuel in timed sequence in quantities that vary as direct functions of pressure applied to the injectors,
• fuel pressurizing means for pressurizing a source of fuel to varying pressure levels as a function of operator demand and engine operating parameters,
• passageway means for connecting the output of said fuel pressurizing means to said fuel injectors,
• the improvement comprising a valve means interposed in said passageway means, said valve means comprising:
• a housing having an inlet connected to said fuel pressurizing means and a flow path leading from said inlet to the passageway means supplying pressurized fuel to a portion only of the fuel injectors for said engine,
• a plunger displaceable between a first position wherein it blocks flow through said flow path and a second position wherein said plunger presents a negligible resistance to flow therethrough, said plunger providing a controlled rate of flow area increase between said first and second positions,
• means for urging said plunger toward said first position whenever the fuel system is below a predetermined level and for urging said valve toward said second position whenever the pressure is above said predetermined level,
• whereby a portion of the cylinders of said engine are motored during certain operating conditions to minimize engine exhaust emissions.