Consider the fuel pump the heart of the fuel system. It provides a constant supply of fuel to the fuel rail to ensure that the injectors always have enough fuel to work with. However, when the power output is significantly increased over stock the motor becomes hungrier and the injectors need more fuel to maintain proper air fuel ratios. (This is especially true under boost.) An upgraded fuel pump is often installed to ensure that a boosted motor has the pumping capacity to maintain the proper fuel pressure. With significant gains over stock output planned for project S2000, it has been fitted with a Walbro 255 high flow fuel pump.
Prepare the Car:
When prepping the car, park the car in a well ventilated area (outside is ideal) and then depressurize the fuel system. To depressurize the system, located the fuse block under the driver’s side dash near the pedals and remove the fuel pump fuse. The fuel pump fuse is the second fuse from the bottom on the left column. (blue, or check the fuse diagram) With the fuse removed, start the car and let it idle until it stalls. Once stalled, replace the fuse and open the hood and disconnect the battery terminals. (Disconnect the black ground (-) first and then the red (+) cable.
Remove the fuel pump fuse to depressurize the fuel lines. (Blue fuse, 2nd from bottom on left column, pointed to by the metal pick.)
Locate and Remove the Factory Fuel Pump:
The fuel tank on the S2000 is toward the mid of the car which means the fuel pump is located under the soft top. To access the fuel pump panel, remove the trunk lining near the spare tire and then the lining right to the left. The fuel pump lid is now visible but go ahead and remove the spare to give yourself more room to work. Remove the bolts holding the lid and the top of the fuel pump assembly and fuel tank will now be visible. On the assembly, disconnect the electrical plug first and then remove the 8 small bolts that secure the assembly to the fuel tank as well as any brackets holding non fuel lines. At this point the two fuel lines are still connected at the top even though the assembly is now loose. Even with the fuel system depressurized, there is still residual fuel in the fuel lines so lift the assembly about an inch out of the fuel tank and then disconnect the two fuel lines and immediately move them to the 1 inch opening between the top of the assembly and the fuel tank. (This just helps reduce the mess from excess fuel. The residual fuel will now drain out of the lines and into the fuel tank.) Finally, complete lift the fuel pump assembly out of the fuel tank to the outside of the car.
Image taken through the rear glass showing the fuel pump lid (1) and the fuel pump assembly location (2)
Labeled components of the top of the fuel pump assembly.
The fuel pump assembly removed from the S2000.
Installing the Walbro Pump
With the assembly out, remove the factory pump by first removing the plastic clip and rubber grommet from the bottom of the assembly. Then remove the filter by removing the small c-clip from the bottom of the pump. (This is a circular metal clip located at the center of the pump. Pry it off with a flathead) Finally, remove the electric plug from the top of the pump and then remove the short fuel line. The factory pump will fall out of the assembly. Now install the Walbro in the reverse process as the removal of the factory unit. Slide the Walbro pump into the assembly and connect the new fuel line to the fuel outlet and then reconnect the electric plug. Reattach the filter to the bottom and secure it with the small clip. Slide the grommet and plastic clip back in place. Finally, careful insert the assembly back into the fuel tank. (take care not to catch the fuel level float on anything) And then reattach the fuel lines, the 8 bolts around the top, the electric plug and the brackets. Leave the lid off for the time being.
Labeled image showing the major components of the fuel pump assembly. The fuel pump resides in the center.
Testing the Pump
Before reinstalling the rear trunk trim, go ahead and reconnect the battery to return power to the car. (reconnect (+) first and then (-)) Place the key in the one position and the fuel pump will prime. (You will be able to hear it) Go to the rear of the pump and check the fuel lines for any leaks. If no leaks are present, go ahead and start the car and check for any fuel leaks one more time. If no leaks again, go ahead and reinstall the lid and the trunk trim. The fuel pump install is now complete.