The fuel pump is a component found in most combustion engines, which feeds fuel from the gas tank into the fuel injector or carburetor. In a carbureted engine, the fuel pump is usually fairly low-pressure, whereas in a fuel-injected engine it is a high-pressure pump mounted inside of the gas tank. Changing a fuel pump is a moderate-level mechanical job, and can be attempted by most people with a decent understanding of how their car works. Changing a fuel pump shouldn’t be attempted by people without any background in home auto repair, as the potential to damage equipment is relatively high for the inexperienced.
Most modern cars contain an electric fuel pump, which is almost always located inside of the gas tank itself. Placing the fuel pump submerged in liquid gasoline makes for a safer car in many ways, including the fact that by submerging the electrical equipment in liquid gasoline, which is not flammable, you reduce the chances of an electrical spark causing an explosion. A fuel pump generally constantly pumps gasoline to the engine, and gasoline not used is simply returned back to the gas tank. An additional component of an electric fuel pump is an electronic control unit, which regulates the fuel pump’s operation, leading to added safety. In some cases changing a fuel pump in a car will not fix the fuel pump problem, in which case it is likely the electronic control unit that is at fault.
Before changing a fuel pump, you’ll want to make sure the fuel pump itself is the problem. The fuel lines should be checked first, as they can be clogged or restricted, leading to insufficient fuel being pumped. The pressure regulator can also be broken, leading to a loss of fuel pressure, which can appear to be a broken fuel pump. And the wiring itself could be at fault, with a fuse blown or some sort of electrical short taking place and limiting the ability of the fuel pump to function properly. If none of these things seem to be wrong, however, changing a fuel pump may be your only option.
First, you’ll need to find a replacement fuel pump. Most cars have advanced manuals available online, or you can order physical copies of them from your manufacturer or a third party. This will let you know what kind of fuel pump you need, and you can then either order one direct, or find one in a junkyard for a reduced price. The manual will also let you know how to access the fuel tank on your car.
If you’re lucky, your vehicle will have an access panel beneath the floor of the trunk or underneath the back seat. You can then access the fuel plate, which can usually be loosened by a few bolts. Once loose, you can remove the plate, the fuel pump itself, and the sending unit. At this point, it may be apparent that the fuel pump was simply dirty, and steam cleaning the unit and letting it dry may be sufficient to fix any problems. Otherwise, simply put the new fuel pump back where the old unit was, along with the new filter that came with the pump, and preferably change any gaskets or seals which are cracked, as well as any fuel lines that show signs of wear.
If there isn’t an access panel beneath the trunk or back seat, changing a fuel pump is a much more difficult task, and is usually worth having a professional do. Otherwise, you’ll need to raise the car up, with the vehicle supported with at least two jack stands. Then you can remove the filler neck from the fuel tank, disconnect the fuel straps, lower the entire tank down, and disconnect the wiring, hoses, and fuel line. Then the tank can be removed, and the earlier steps can be accomplished.