Replacing The Fuel Pump In Your Classic 1989 Mustang

Changing the fuel pump on a 1989 Mustang is a simple process that can be done at home with the right tools and knowledge. The fuel pump is located in the fuel tank, and the procedure for replacing it is similar to that of other Mustang models from the same era. The process involves clamping the fuel line to stop the flow of fuel, removing the old fuel pump, and installing a new one. It is recommended to replace the fuel filter and rubber pipes at the same time to avoid any potential leaks. When working with fuel, it is important to take safety precautions such as wearing protective gear and avoiding smoking.

Disconnect the fuel lines

Disconnecting the fuel lines is a crucial step in changing the fuel pump on a 1989 Mustang. Here is a detailed guide on how to do it:

First, you need to stop the flow of fuel from the fuel tank. In the case of the 1989 Mustang, the fuel pump works off a cam from the engine, so the pump will only move the fuel when the engine is running. As a precaution, you should clamp the fuel pipe to stop any drips or residual fuel leaks. Use a simple screw-type clamp to squeeze the rubber pipe and prevent fuel flow.

Next, you will need to remove the connection to the fuel pump. There may be different types of clips or clamps holding the rubber pipe in place, such as crushed (lemon) style clips or a simple jubilee clip. If you have a jubilee clip, you can simply undo it. However, if you have the lemon-style clips, you may need to cut the rubber pipe to start the removal process.

Once you have removed the connection to the fuel pump, there may still be fuel in the lines, so be prepared for any remaining fuel to run out. Place a drip tray or receptacle underneath to catch any fuel and avoid spills.

Now, you will need to disconnect the other side of the fuel filter if your Mustang has one. You can either cut or disconnect, whichever you prefer. If you choose to disconnect, be aware that there may still be fuel in the lines.

At this point, you should have successfully disconnected the fuel lines from the fuel pump and filter. The next step would be to remove the fuel pump itself, which is held in place by two bolts. You can now proceed with installing the new fuel pump, ensuring a proper seal and secure connections for the fuel lines.

Remember to work with fuel safely. No smoking, protect your eyes and skin, and use common sense!

Remove the bolts

To remove the bolts, you will need to first determine which of the two bolts you want to undo first. This will depend on your setup, including the presence of a steering pump or air conditioning brackets that could block access to the pump bolts.

Once you have decided which bolt to start with, break it free and undo it about halfway so you can move the pump. This will help you determine the location of the fuel pump cam. If the fuel pump is under a strong spring load, the cam is likely activating the pump. You can then crank the engine by hand until the pressure on the fuel pump arm is at its lowest tension. This will make repositioning the fuel pump back onto the block easier when refitting.

After you have undone the first bolt, repeat the process for the second bolt. Fully remove both bolts and then take the fuel pump out of the engine block. Be careful not to let anything fall into the engine block, and take care with any broken gasket and debris.

You may find that part of the gasket is still stuck to the pump face and the engine block. If so, you will need to clean the engine block surface to ensure the gasket will make a good seal. Use a razor blade scraper, always working away from the opening and working from the centre outwards.

Clean the engine block surface

To clean the engine block surface of your 1989 Mustang, you will need to remove the old gasket and any remaining residue. This can be done with a razor blade, holding it vertically to the surface and going over the block to clean it flat. Be careful not to nick or score the surface. Alternatively, you can use a gasket scraper tool or a sharp scraper. You can also use a die grinder and wire wheel on an iron block to gently remove the gasket without gouging the surface.

Once the majority of the gasket material has been removed, you can use a cleaner to remove any remaining residue. Acetone is recommended for this purpose, applied with a clean, lint-free rag or disposable shop towel. Be careful not to use too much acetone, as it is powerful stuff. You can also use lacquer thinner and a towel, or brake cleaner, to clean the surface. It is important to ensure that the surface is completely free of oil before installing the new gasket.

After cleaning, inspect the engine block surface for any imperfections. If there are small imperfections, you can use a fine Scotch-Brite pad to smooth them out. However, be careful not to overdo it, as the RA finish specs for heads/decks are pretty smooth and require top-of-the-line tooling to create. If there are more significant imperfections, you may need to have the block resurfaced.

Reattach the metal carb pipe

To reattach the metal carb pipe, you will need to follow these steps:

Firstly, you will need to tighten the pipe into the mounting. Depending on the design of your pump, you may need to hold the mounting point nut with another spanner to avoid breaking the spot weld on the pump. If you have a concourse pump replacement, this step is not necessary as the casting is all in one.

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

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 you can start with the filter empty and observe any fuel in the filter being pulled in by the pump itself when cranking over without starting the engine.

When connecting back 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 to ensure they are all secure. You don't want a fuel leak or oil leaking from the back of the pump.

Attach the input line

To attach the input line of the fuel pump, you will need to follow these steps:

Firstly, you will need to determine the location of the fuel pump cam. The fuel pump is under a strong spring load, so the cam is likely activating the pump. To do this, crank the engine over by hand until the pressure on the fuel pump arm is at its lowest tension.

Now, you can start to reconnect the fuel lines. You will need to attach the input line of the fuel pipe to the male part of the fuel filter. Make sure to use the correct tool to attach the 'lemon' clip or single ear clip; pliers are not recommended. There will be a flow arrow for the direction of the fuel on the filter, so ensure that you get the flow direction correct, pointing to the fuel pump. Alternatively, you can use a jubilee clip to attach the pipework.

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 onto the male fitting of the fuel pump and secure it in place with a clip or 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, you can start with the filter empty, so 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 that the clips and bolts are all secure. You don’t want a fuel leak or oil leaking from the back of the pump.

Frequently asked questions