A 2.9L is a 6 cylinder so if it is a 2.9L it is a 6cyl. not a 4cyl. There are 2 fuel pumps on a 2.9L a low pressure pump is inside the tank and a second pump along the frame rail under the drivers side door area. They both are supplied power from the same wires. Check the wires at the high pressure pump. The black with the purple stripe is the power side the solid black is the ground. The wires go from the high pressure pump to the lower pressure pump thru the same wire harness. So if you have power and ground at the high side pump you should have it a the low side pump unless the harness is damaged after the high pressure pump. Do you have any pressure usually you'll get low pressure when the high side pump is bad and no pressure when the low side pump is bad.