How to Replace a Fuel Pump on a 1984 Ford Mustang

The 1984 Ford Mustang uses a mechanical pump, which is driven off an eccentric lobe on the forward end (radiator end) of the camshaft. An engine-driven mechanical pump has an average of 4 to 6 pounds of fuel pressure. It uses a rubber diaphragm to draw fuel from the tank and supply it under pressure to the carburetor. The diaphragm is the major cause of failure in a mechanical pump.

Tools Used: Set of line wrenches, Ratchet, Set of socket wrenches, RTV silicone

Replace a Fuel Pump

Remove the inlet and outlet fuel lines on the pump using a line wrench. The fuel pump is located on the front of the engine bolted to the timing chain cover. Loosen the two bolts on the fuel pump, but do not remove them yet.

Rock the pump to feel if the eccentric lobe is pushing down on the pump arm. The eccentric is shaped like an egg. When the top pinnacle end is down, it pushes the arm of the pump down. It will feel tight and be difficult to rock up and down if this is the case. You want the arm to be on the low side of the eccentric so there is very little pressure on the arm for ease of replacement. If the bolts are removed with the eccentric pushing down on the rod, the pump will be difficult to install. If there is no pressure, remove the bolts and pull the pump out of the housing. If there is pressure, place a socket wrench on the crankshaft center bolt and turn the engine clockwise a small amount to turn the eccentric to the low side.

Rock the pump again. If there is still pressure, turn the engine a little farther until the pump will rock easily.

Spread some RTV sealant on both sides of the new gasket and place the gasket on the pump. Install the pump and tighten the bolts securely. Install the inlet and outlet fuel lines and tighten them with the line wrench.

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