A fuel pump comprising: a fuel pump housing with a pumping chamber defined therein, said fuel pump housing having an inlet valve bore which is connectable to a source of fuel via a pump housing inlet passage, said inlet valve bore extending along an inlet valve bore axis and being stepped such that said inlet valve bore includes a shoulder which is traverse to said inlet valve bore axis; a pumping plunger which reciprocates within a plunger bore along a plunger bore axis such that an intake stroke of said pumping plunger increases volume of said pumping chamber and a compression stroke of said pumping plunger decreases volume of said pumping chamber; and an inlet valve assembly comprising: a valve seat with a valve seat flow passage extending therethrough, said valve seat being located within said inlet valve bore such that said valve seat abuts said shoulder and is urged toward said shoulder by pressure within said pumping chamber during said compression stroke; a valve member which is moveable between 1) an unseated position which provides fluid communication through said valve seat flow passage and 2) a seated position which prevents fluid communication through said valve seat flow passage, the valve member including a valve member central portion which is a flat plate with valve member passages extending therethrough, the unseated position permits flow through valve seat flow passages and such that valve seat flow passages being in fluid communication with the pumping chamber. a fuel pump housing with a pumping chamber defined therein, said fuel pump housing having an inlet valve bore which is connectable to a source of fuel via a pump housing inlet passage, said inlet valve bore extending along an inlet valve bore axis and being stepped such that said inlet valve bore includes a shoulder which is traverse to said inlet valve bore axis; a pumping plunger which reciprocates within a plunger bore along a plunger bore axis such that an intake stroke of said pumping plunger increases volume of said pumping chamber and a compression stroke of said pumping plunger decreases volume of said pumping chamber; and an inlet valve assembly comprising: a valve seat with a valve seat flow passage extending therethrough, said valve seat being located within said inlet valve bore such that said valve seat abuts said shoulder and is urged toward said shoulder by pressure within said pumping chamber during said compression stroke; a valve member which is moveable between 1) an unseated position which provides fluid communication through said valve seat flow passage and 2) a seated position which prevents fluid communication through said valve seat flow passage, the valve member including a valve member central portion which is a flat plate with valve member passages extending therethrough, the unseated position permits flow through valve seat flow passages and such that valve seat flow passages being in fluid communication with the pumping chamber. a valve seat with a valve seat flow passage extending therethrough, said valve seat being located within said inlet valve bore such that said valve seat abuts said shoulder and is urged toward said shoulder by pressure within said pumping chamber during said compression stroke; a valve member which is moveable between 1) an unseated position which provides fluid communication through said valve seat flow passage and 2) a seated position which prevents fluid communication through said valve seat flow passage, the valve member including a valve member central portion which is a flat plate with valve member passages extending therethrough, the unseated position permits flow through valve seat flow passages and such that valve seat flow passages being in fluid communication with the pumping chamber.