The vehicle in question is a Vauxhall Cavalier, but the guide below for replacing the fuel pump will be a very similar process for most vehicles.
Estimated time: 3-4 Hours Difficulty: Medium
First of all remove the battery, negative first and then positive as this will stop there being any sparks.
Begin by removing the pressure from the fuel pump. This is done when the engine is running. You do this by accessing the relay box and pulling out the relay for the fuel pump. The engine will stop running as there will be no fuel pumping through the engine.
Spray some WD-40 onto the bolts that hold up the fuel tank and unscrew the screw holing the clamp onto the fuel hose. Once you’ve removed the clamp, disconnect the fuel hose from the vehicle; disconnect any other wires or connections going to the fuel tank.
You will need to disconnect the fuel lines to the fuel filter, but be careful as some fuel may spill out here, so get something to catch the fuel. You will also need to remove the bolts on the heat plate between the exhaust and tank so you can remove the tank from the vehicle.
You will need to prop up the fuel tank as you prepare to remove the bolts for the strap holding up the tank. Once you have removed the strap, take the tank off and place it on the floor.
Now disconnect any harnesses, wires or connections to the locking ring. Get a hammer and chisel and start moving the locking ring to open this up. Once unlocked the locking ring will spring up, then you pull the pump out from the fuel tank.
Fitting the new fuel pump
Once the fuel pump is pulled out follow the steps below to fit in the new fuel pump.
Replace the old o-ring with the new one and put the new fuel pump back inside the tank, locking the locking ring back in place. Re-connect all connections to the pump and prop the tank back into position using a jack.
Bolt the strap back over the tank, connect the fuel lines to the fuel filter and re-connect the hoses. Re-connect all electrical connections and bolts, ensuring everything is tightly in place. Bolt the heat plate back in place.
Now put the fuel pump relay back in the relay unit and close the unit. Re-connect the battery, positive first then negative, in order to avoid any sparks.
Start the engine now to ensure the fuel is being pumped around the vehicle. If it starts ok, check underneath the vehicle to make sure there are no leaks anywhere.