Description: A mechanical fuel pump is
most often used on cars with carburetors. This type of pump produces
low pressure and is usually driven by the engine. Cars all use
electric fuel pumps nowadays because of the universal application
of fuel injection and its need for higher pressures. Electric fuel
pumps are almost always located inside the gas tank, but there are
some applications where the pump may be located along the
frame or unibody channel. The
pump has a strainer at its pickup to filter out
contaminants and uses an electric motor for power. Fuel is
used as a lubricant and coolant for
the motor. The electric
fuel pump has its own electrical control circuit, typically consisting of wiring, a fuse and a relay. This circuit interacts with the car’s powertrain control module (PCM), which governs and monitors fuel pump operation.
Purpose:
The fuel pump provides fuel with
the proper pressure and volume for delivery by the carburetor or fuel
injection system. The electric fuel pump circuit also employs
various
safeties that stop the pump from running in the event of
an accident.
Maintenance Tips/Suggestions: Mechanical fuel pumps require no
maintenance, but should be replaced at the first sign of a problem.
Pressure or volume may drop off, giving an early warning sign of
impending pump failure. A professional service technician can usually identify
a pump problem quickly. With fuel-injected vehicles, regular fuel
filter changes can help extend the life of the
electric fuel pump. It's best to replace the filter every two years or
24,000 miles. A contaminated filter can restrict fuel flow from
the electric fuel pump, eventually taking a toll on its life.
You can also help protect the pump by keeping the tank at least
¼ full at all times. Since fuel cools the pump, having
plenty of fuel in the tank helps keep the pump from
getting too warm, which could damage it. Another
good reason to keep the gas tank at least ¼ full
is to reduce the chances of sediment pick-up at the fuel
pump inlet strainer. A restricted strainer can starve the pump,
causing it to overheat and fail. If you own a
Ford or Lincoln-Mercury vehicle, check your owner’s manual for the location
of the fuel pump shut-off switch. This switch is designed to
electrically disconnect the fuel pump in the event of an accident. Sometimes, an
abrupt jarring of
your car may be enough
to cause this switch to open. It’s good to know where
the switch is so you can try resetting it
if your car does not start. A faulty electric fuel pump
can cause various symptoms including a loud pump whine, engine no-start,
hesitation, poor performance and stalling. If your car demonstrates any of
these performance problems, have it checked out
by a qualified service technician. Replacing the fuel pump generally
involves removal of the fuel tank.
