19. If you have no fuel flow or low pressure, it could be a bad pump (HFCM), OR it could be a plugged fuel filter or plugged lines. You can blow air through the lines to check for plugging. If there is no pluggage, test the pump. First, pull fuse 302 (PCM) and relay 304 (FICM) and then pull the secondary (upper) fuel filter, remove any fuel, and then verify that it is being filled by cranking the engine. As it is being filled, make sure there are no air bubbles. If there are, you have a leak in some connections, the HFCM suction line, or the HFCM o-ring (most likely). Be sure to lube the o-ring w/ oil before re-installing.