Fuel System Malfunction - Diagnosis; Lift Pump - Dodge D250 1990 Service Manual

Fuel System
DODGE Turbo Diesel
Fuel System Malfunction - Diagnosis
Page 14-3
Fuel System Malfunction - Diagnosis
The function of the fuel system is to Inject clean, atomized fuel
Into the engine cylinders at a precise time near the end of the
compression stroke of each piston. The components of the
system contribute to the delivery of fuel to the cylinders.
Lift Pump
Note; A malfunctioning lift pump can cause low power.
The lift pump is mechanically driven by a lobe on the camshaft.
Wear on the lever or a damaged lobe can reduce the pumping
action.
Do not operate the fuel system with a suction restriction (A) of
more than 95mm (3.75 inch) Hg.
Caution; If the diaphragm ruptures, fuel will drain from
the weep hole (B) In the housing.
A
Cheeky
Valves
Diaphragm
Pressure drop across the filter is 21 kPa [3 psi], maximum.
The pressure drop will increase as the filter removes
contamination from the fuel. Therefore, a worn lift pump will
have reduced capacity to force fuel through a dirty filter. This
can cause low engine power.
Note: Frequent filter replacement to get full power from the
engine can indicate a worn lift pump.
The output of the pump can be measured at cranking speed:
• Volume (within 30 seconds): 0.75 liters [0.70 U.S. quarts]
• Pressure: 21 to 35 kPa [3 to 5 psi]
ON