How to Find the Fuel Pump on a 1981 Bronco

The 1981 Ford Bronco was equipped with the 4.9-liter, 300 cubic-inch, in-line six-cylinder, 5.0-liter, 302 cubic-inch V-8 or 5.8-liter V-8 engine. The 4.9-liter engine uses a one-barrel carburetor. The 5.0-liter, and 5.8-liter engines use two-barrel carburetors. All use a mechanical fuel pump mounted on the engine, although in slightly different positions. These fuel pumps are much easier to access than those on later fuel-injected engines. Fuel injection did not become standard on the Bronco until 1985.

Mechanical Fuel Pumps

Mechanical fuel pumps use a vacuum diaphragm to draw fuel from the tank and send it to the carburetor. An arm on the fuel pump rides on an eccentric attached to the camshaft timing gear, or part of the camshaft. This eccentric works in a manner similar to a camshaft lobe. As the camshaft or gear turns, the eccentric pushes the arm on the fuel pump up and down, actuating the diaphragm and causing fuel to flow. Mechanical fuel pumps work at a low pressure of between three and five psi.

4.9-Liter Engine

The fuel pump on the 4.9-liter engine is located on the driver side of the engine block, next to the No. 2 cylinder -- the second cylinder from the front of the engine. If you follow the fuel line from the carburetor, it will lead you to the fuel pump.

5.0-Liter and 5.8-Liter Engines

The fuel pump on the 5.0-liter and 5.8-liter engines is attached to the timing cover at the front, driver side of the engine, below the water pump. Once again, if you follow the fuel line from the carburetor, it will lead you to the fuel pump.

Removal and Installation

The procedure for removing these pumps is the same on either engine. Unscrew the fuel lines from the fuel pump with a flare nut wrench. Use a ratchet and socket to remove the two bolts that hold the pump onto either the engine block or timing cover. Scrape the gasket surfaces with a putty knife to remove any gasket material or debris. Clean the gasket surfaces with a shop rag wet with parts cleaner. Coat the gasket surfaces and both sides of the gasket with black RTV silicone. Mount the gasket onto the fuel pump and mount the pump onto the engine block or timing cover. Install the bolts and use a torque wrench to torque them to between 19 and 27 foot-pounds. Install and tighten the fuel lines.

Fuel Pump Not There?

While these engines all used mechanical fuel pumps, a popular conversion was the installation of an electric fuel pump. You may see the mechanical pump on the engine with no fuel lines attached to it, or there may be a metal plate -- called a block-off plate -- bolted to the engine where pump should be. If this is the case, the Bronco has been modified with a universal electric fuel pump. Since these pumps are designed to push fuel rather than pull it, they are usually located on the frame, very close to the fuel tank. Follow the fuel line from the carburetor, back along the frame and you will find it.