Replacing Mechanical Fuel Pump In Ford 302: Step-By-Step Guide

Replacing the mechanical fuel pump on a Ford 302 is a fairly simple task that can be completed in about half an hour. The fuel pump works on a sprung-loaded arm that sits under a cam inside the engine block, with one side sucking fuel into it and the other pushing fuel up to the carburettor. Before beginning the replacement, it is important to clamp the fuel flow from the tank and place a drip tray to catch any fuel that may leak out. The pump is connected to the fuel filter and carburettor by rubber pipes, which should be cut or disconnected. The pump itself is held in place by two bolts, which need to be removed to take out the pump. When installing the new pump, it is important to ensure that the arm goes under the cam lobe – this may require greasing to ease the process. The pump bolts can then be tightened, and the fuel lines and carburettor reconnected.

The fuel pump cam

The camshaft drives the fuel pump by pushing down on the pump arm, so it is essential that the arm is properly lubricated and positioned correctly. Failure to do so can result in damage to the pump. It is also important to ensure that the dowel pin is in the correct position, as this can affect the alignment of the cam and pump.

When installing a new fuel pump, it is worth checking the condition of the camshaft. Over time, the cam can become worn, which can affect the performance of the fuel pump. In some cases, you may need to replace the camshaft along with the fuel pump to ensure optimal performance.

Additionally, when working with the camshaft, it is crucial to be aware of the different types of cams available for the Ford 302 engine. Some engines use a one-piece cam eccentric, while others use a two-piece design. Using the wrong type of cam can result in fitment issues, so it is important to verify which type is required for your specific engine.

The gasket

Types of Gaskets

There are different types of gaskets available for your Ford 302's fuel pump. Some fuel pumps come with a single gasket, while others may provide two gaskets. It's important to use the correct type and number of gaskets as specified by the manufacturer. Additionally, you can find fuel pump block-off plate gaskets, which are used when blocking off the fuel pump mounting point on the engine.

Gasket Materials

Fuel pump gaskets are typically made of thin, flexible material, such as paper, rubber, or a composite material. These gaskets create a tight seal between the fuel pump and the engine, preventing fuel and oil leaks.

Preparing the Gasket

When installing a new fuel pump gasket, it's essential to prepare the surface properly. Clean the mounting surface on the engine block and the fuel pump to ensure there is no dirt, grease, or residue. You can use a die grinder to smooth out any inconsistencies or pitting on the mounting surface, improving the seal.

Using RTV or Gasket Sealant

Some mechanics recommend applying a thin coat of RTV (room temperature vulcanizing) silicone or gasket sealant to both sides of the gasket. This can enhance the seal and prevent leaks, especially on older engines with pitted or inconsistent surfaces. However, be cautious when using RTV, as excessive amounts can flake off and cause internal issues. Always follow the manufacturer's instructions when using RTV or gasket sealant.

Installing the Gasket

When installing the gasket, ensure that it is correctly aligned and seated properly. The gasket should fit snugly between the fuel pump and the engine block. Refer to the fuel pump installation instructions for the correct placement of the gasket. Tighten the bolts securely, but be careful not to overtighten, as this can damage the gasket and affect the seal.

Testing for Leaks

After installing the new fuel pump and gasket, it's crucial to test for leaks. Start the engine and inspect for any signs of fuel or oil leaks around the fuel pump. If you notice any leaks, recheck the gasket's alignment and ensure that the bolts are tightened correctly. If the leak persists, you may need to replace the gasket or apply a gasket sealant.

Remember to follow safety precautions when working on your vehicle, especially when handling fuel system components. Always refer to the manufacturer's instructions or seek advice from a qualified mechanic if you're unsure about any steps in the process.

The input and output of the fuel pump

The input and output of a fuel pump are integral parts of a vehicle's fuel system. The fuel pump is a high-pressure assembly that delivers fuel from the tank to the engine for combustion.

Input

Fuel enters the pump from the fuel tank. This can be through a fuel line or via a direct connection to the tank. In some cases, the pump may be submerged in the fuel tank.

Output

The output of the fuel pump is high-pressure fuel that flows to the engine. This fuel passes through a filter and, in some cases, a fuel pressure regulator before reaching the engine's fuel injectors. The fuel injectors are designed to handle a specific quantity of fuel at a given pressure.

Factors Affecting Fuel Pump Output

Several factors can influence the output of a fuel pump:

• Volume of Fuel: The amount of fuel available at the pump inlet affects the output.
• Delivery Line Capacity: The size and condition of the fuel lines can impact the pump's ability to deliver fuel.
• Pump Ability: The pump's capacity to generate sufficient fuel volume and pressure is crucial.
• Supply Voltage: Lower voltage to the pump can result in reduced volume output.
• System Pressure: While fuel pressure does not increase the flow, it is necessary to sustain it.

Removing the pump

To remove the pump, first stop the flow of fuel from the fuel tank. These types of pumps work with a cam from the engine, so the pump will only move the fuel when the engine is running. As a precaution, clamp the fuel pipe to stop drips or residual fuel leaks.

Next, disconnect the connection to the fuel pump. There may be crushed (lemon) style clips or a simple jubilee clip. If you have a fuel filter, you can either cut or disconnect it.

The output side of the fuel pump should have a metal pipe that goes up to the carburettor. Unscrew this pipe from the fuel pump. Be prepared for any remaining fuel to run out.

The fuel pump body is held in place by two bolts. Undo these bolts and remove the pump from the engine block. The fuel pump may have part of the gasket still stuck to it. Take care not to let anything fall into the engine block and take care with broken gasket debris.

Scrape any remaining gasket from the engine block, working from the centre outwards. Then, clean the engine block surface to ensure the gasket will make a good seal.

There are a couple of ways to remove this pump. One option is to break the bolts free and undo them halfway so you can move the pump to determine the location of the fuel pump cam. Then, fully remove the bolts and the pump. This makes it easier to align the new pump when refitting.

Alternatively, you can simply unbolt the pump and refit the new one. However, this may make it more difficult to align the pump while inserting the bolt to the block.

Reattaching the metal carb pipe

First, you will need to attach the input line of the fuel pipe onto the male part of the fuel filter. Using a 'lemon' clip or a single ear clip with the correct tool makes it look neater. There will be a flow arrow for the direction of the fuel on the filter, make sure you get the flow direction correct pointing to the fuel pump. You can, of course, use a jubilee clip to attach the pipework if you prefer, or don’t have the correct tool to pinch the clip tight.

Next, make sure that the rubber fuel pipe is not kinked and forms as straight a route as possible to the fuel pump. Place the tubing to the fuel pump (male fitting) and secure it in place, either with a clip or a jubilee clip. Note the fuel flow direction arrow on the plastic filter.

You could fill the filter with some fuel so it’s ready and primed. Or start with the filter empty, as then any fuel you see in the filter has been pulled into the filter by the pump itself when being cranked over without actually starting the engine.

When connecting back up to the fuel line coming from the inner fender, undo the clamp previously put in place to stop fuel seeping, and slip the new rubber pipe back over the fuel line.

Finally, re-check the two bolts to the block and the clips are all secure. You don’t want a fuel leak or oil leaking from the back of the pump.

Frequently asked questions