shown at 174 176 and 178 in fig6 however the pintle 186 has nose 196 that extends into the cylindrical volume 194 and cylindrical collar 198 is closely spaced from the cylindrical bore wall of volume 194 the nose 198 extends with a bullet shaped tip 200 into a conical flow volume 202 that enlarges from the end of the cylindrical volume 194 the shape of the tip also has an effect on the back pressure as in previously described embodiments when the control valve 186 lifts off seat 192 the fluid flow is throttled into low pressure chambers 202 204 which in turn is in fluid communication with a sump at substantially ambient pressure as described with respect to fig2 the low pressure chambers such as 120 120 u2032 and 204 from each injector are connected to a common drain line 122 and a low resistance valve 122 u2032 between the drain line and the fuel tank 123 provides a baseline pressure on the order of 3 10 psi in the low pressure chambers in general the drain includes a line from the injector to a fuel reservoir at ambient pressure and the drain line includes means for maintaining fuel at the injector drain outlet to the drain line at a pressure of at least about 3 psi above the pressure in the reservoir fig8 presents another embodiment 206 which incorporates features from fig4 and 7 but has a different pressure regulating valve pintle 208 passes through control chamber 210 for sealing against seat 212 and has an extension with cylindrical throttle collar 214 in.