TM 5-2420-230-24-2
Fuel Lift Pump (005-045)
B3.9 and B5.9 Series Engines
Page 5-78
Section 5 - Fuel System - Group 05
Normal pressure drop across the fuel filter is 35 kPa [5 psi],
maximum.
The pressure drop will increase as the fuel filter removes
contamination from the fuel. Therefore, a worn fuel transfer
pump will have reduced capacity to force fuel through a
dirty fuel filter. This can cause low engine power.
NOTE: Frequent fuel filter replacement to get full power
from the engine can indicate a worn transfer pump.
The output of the fuel transfer pump can be checked two
ways:
Test 1: Measure the output pressure using an in-line pres-
sure gauge installed between the filter head and the fuel
injection pump.
Test 2:
Measure the flow volume.
Test 1: Output Pressure Test (Diaphragm Style)
Start the engine, and measure the output pressure of the
fuel transfer pump using an in-line pressure gauge.
Minimum pressure at rated speed is 21 kPa [3 psi].
Test 2: Flow Volume Test (Diaphragm Style)
CAUTION
To prevent the engine from starting, disconnect the fuel
shutdown wiring. Residual fuel in the injection pump
can cause the engine to start.
CAUTION
Do not crank the starter for more than 30 seconds at a
time. Doing so can result in starter damage.
L-938
