A motorist comes into your shop and says that his vehicle is losing
power even though the engine is surging.
You check it out yourself
and find there is no way to use the pedal to control the amount of thrust
you get from the engine. You figure there's a problem with the fuel pump.
car isn't a model you're familiar with, so you pull out one of your handy
manufacturer's repair manuals. You open it to the right section, the one on
the fuel system.
You read through the section. Write down a list of
the tools needed and a brief summary of the repair procedure.
FUEL SYSTEM COMPONENTS
Mechanical Fuel Pump
mechanical fuel pump is used on the 1982 carbureted engines. It's of the diaphragm-type
and because the design is serviced by replacement only, no adjustments or
repairs are possible. The pump is operated by an eccentric on the camshaft.
the Fuel Pump
To determine if the fuel pump is in good condition,
tests for both volume and pressure should be performed. The tests are made
with the pump installed, and the engine at normal operating temperature and
idle speed. Never replace a fuel pump without first performing these simple
Be sure that the fuel filter has been changed at the specified
interval. If in doubt, install a new filter and then test the system.
- Disconnect the fuel line at the carburetor and connect a fuel pump pressure
gauge. Fill the carburetor float bowl with gasoline.
- Start the engine and check the pressure with the engine at idle. If the
pump has a vapor return hose, squeeze it off so that an accurate reading can
be obtained. Pressure should not be below 4.5 psi.
- If the pressure is incorrect, replace the pump. If it's OK, go on to the
- Disconnect the pressure gauge. Run the fuel line into a graduated container.
- Run the engine at idle until one pint of gasoline has been pumped. One
pint should be delivered in 30 seconds or less. There is normally enough fuel
in the carburetor float bowl to perform this test, but refill it if necessary.
- If the delivery rate is below the minimum, check the lines for restrictions
or leaks, then replace the pump.
REMOVAL AND INSTALLATION
The fuel pump is located
at the center rear of the engine.
- Disconnect the negative cable at the battery. Raise and support the car.
- Disconnect the inlet hose from the pump. Disconnect the vapor return hose,
- Loosen the fuel line at the carburetor, then disconnect the outlet pipe
from the pump.
- Remove the two mounting bolts and remove the pump from the engine.
- Place a new gasket on the pump and install the pump on the engine. Tighten
the two mounting bolts ALTERNATELY and EVENLY.
- Install the pump outlet pipe. This is easier if the pipe is disconnected
from the carburetor. Tighten the fitting while backing up the pump nut with
another wrench. Install the pipe at the carburetor.
- Install the inlet and vapor hoses. Lower the car, connect the negative
battery cable, start the engine, and check for fuel leaks.
How would an auto tech handle this problem?