A fuel pump comprising: a fuel pump housing with a pumping chamber defined therein, said fuel pump housing having an outlet valve bore, said outlet valve bore extending along, and being centered about, an outlet valve bore axis; a pumping plunger which reciprocates within a plunger bore along a plunger bore axis which is traverse to said outlet valve 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 outlet valve assembly comprising: an outlet valve seat with an outlet valve seat flow passage extending therethrough, wherein a first portion of said outlet valve seat is aligned with said pumping plunger in a direction parallel to said plunger bore axis and wherein a second portion of said outlet valve seat is not aligned with said pumping plunger in a direction parallel to said plunger bore axis; and an outlet valve member which is moveable between 1) an unseated position which provides fluid communication through said outlet valve seat flow passage and 2) a seated position which prevents fluid communication through said outlet valve seat flow passage, characterised in that said outlet valve seat includes an outlet valve seat slot extending thereinto; said pumping plunger reciprocates between a top dead center position in which volume of said pumping chamber is minimized to a bottom dead center position in which volume of said pumping chamber is maximized; and wherein a portion of said pumping plunger is located within said outlet valve seat slot when said pumping plunger is in said top dead center position; and said outlet valve seat extends along said outlet valve bore axis from an outlet valve seat first end which is within said pumping chamber to an outlet valve seat second end which is outside of said pumping chamber. a fuel pump housing with a pumping chamber defined therein, said fuel pump housing having an outlet valve bore, said outlet valve bore extending along, and being centered about, an outlet valve bore axis; a pumping plunger which reciprocates within a plunger bore along a plunger bore axis which is traverse to said outlet valve 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 outlet valve assembly comprising: an outlet valve seat with an outlet valve seat flow passage extending therethrough, wherein a first portion of said outlet valve seat is aligned with said pumping plunger in a direction parallel to said plunger bore axis and wherein a second portion of said outlet valve seat is not aligned with said pumping plunger in a direction parallel to said plunger bore axis; and an outlet valve member which is moveable between 1) an unseated position which provides fluid communication through said outlet valve seat flow passage and 2) a seated position which prevents fluid communication through said outlet valve seat flow passage, characterised in that said outlet valve seat includes an outlet valve seat slot extending thereinto; said pumping plunger reciprocates between a top dead center position in which volume of said pumping chamber is minimized to a bottom dead center position in which volume of said pumping chamber is maximized; and wherein a portion of said pumping plunger is located within said outlet valve seat slot when said pumping plunger is in said top dead center position; and said outlet valve seat extends along said outlet valve bore axis from an outlet valve seat first end which is within said pumping chamber to an outlet valve seat second end which is outside of said pumping chamber. an outlet valve seat with an outlet valve seat flow passage extending therethrough, wherein a first portion of said outlet valve seat is aligned with said pumping plunger in a direction parallel to said plunger bore axis and wherein a second portion of said outlet valve seat is not aligned with said pumping plunger in a direction parallel to said plunger bore axis; and an outlet valve member which is moveable between 1) an unseated position which provides fluid communication through said outlet valve seat flow passage and 2) a seated position which prevents fluid communication through said outlet valve seat flow passage, characterised in that said outlet valve seat includes an outlet valve seat slot extending thereinto; said pumping plunger reciprocates between a top dead center position in which volume of said pumping chamber is minimized to a bottom dead center position in which volume of said pumping chamber is maximized; and wherein a portion of said pumping plunger is located within said outlet valve seat slot when said pumping plunger is in said top dead center position; and said outlet valve seat extends along said outlet valve bore axis from an outlet valve seat first end which is within said pumping chamber to an outlet valve seat second end which is outside of said pumping chamber.