Basically, mechanical pumps are known to have the following problems as symptoms of deterioration or wear ;
1. Pressure problems
The average fuel pump pressure is over 4.14 bar(414kPa). Mechanical fuel pump pressure may be much lower to between 0.276 bar (27.6 kPa) and 0.414 bar (41.4 kPa). When the fuel pump is not producing enough pressure, it may be subjected to the output pressure test. The two tests that can be performed are :
a. Vacuum test
b. Perform a fuel volume test
2. Fuel system leaks
Most mechanical fuel pumps have a weep hole on the bottom of the unit. When the internal diaphragm leaks, fuel escapes through the weep hole. This is an indication of a malfunction fuel pump. Another common place for a leak to develop is in the rubber hose and the metal tube that leads from the tank to the fuel pump.
3. Engine oil leaks
The fuel pump arm passes through the timing case cover and this arrangement allows the constant rotating motion of the camshaft or crankshaft to drive the arm. Where the fuel pumps mount to the timing case cover a gasket provides a tight seal. Although this gasket is usually reliable, engine vibration can cause the bolts to come loose and oil can seep out around the fuel pump.
1. Pressure problems
The average fuel pump pressure is over 4.14 bar(414kPa). Mechanical fuel pump pressure may be much lower to between 0.276 bar (27.6 kPa) and 0.414 bar (41.4 kPa). When the fuel pump is not producing enough pressure, it may be subjected to the output pressure test. The two tests that can be performed are :
a. Vacuum test
b. Perform a fuel volume test
2. Fuel system leaks
Most mechanical fuel pumps have a weep hole on the bottom of the unit. When the internal diaphragm leaks, fuel escapes through the weep hole. This is an indication of a malfunction fuel pump. Another common place for a leak to develop is in the rubber hose and the metal tube that leads from the tank to the fuel pump.
3. Engine oil leaks
The fuel pump arm passes through the timing case cover and this arrangement allows the constant rotating motion of the camshaft or crankshaft to drive the arm. Where the fuel pumps mount to the timing case cover a gasket provides a tight seal. Although this gasket is usually reliable, engine vibration can cause the bolts to come loose and oil can seep out around the fuel pump.