TM 5-3805-280-24-2
Fuel System
BENCH TEST FUEL SUPPLY PUMP
35
18
The following bench tests can be performed on a supply
pump installed on the engine when the pump is suspected
to be defective. (See MEASURE FUEL SUPPLY PUMP
PRESSURE in Group 115.)
Perform the Vacuum/Pressure Test and Leakage Test,
listed below. Replace the supply pump if either test shows
the pump to be defective, there is no repair procedure.
VACUUM/PRESSURE TEST:
A--Lever
NOTE: This test will give a good indication of condition of
B--Outlet Side of Pump
both the inlet and outlet valves, as well as the
C--Inlet Side of Pump
diaphragm. The numerical values obtained on
D--Primer Lever
both the vacuum and pressure sides are not
important; rather it is the needle movement that is
important (very slow for a good pump; very fast or
not at all for a defective pump).
1. Remove inlet and outlet fittings.
2. Install vacuum/pressure gauge to inlet side of pump
(C).
3. Move primer lever (D) all the way downward. Release
lever and at the same time observe gauge:
The gauge needle should read the same value each
time, and then very slowly return to "0". This
indicates that the inlet valve and diaphragm are in
good condition. Proceed to next step.
If the gauge needle does not move at all, or the
needle rapidly returns to "0", the pump is defective
and must be replaced.
4. Remove vacuum/pressure gauge and install onto outlet
side of pump (B).
5. Move priming lever all the way to upward position.
Release lever and at same time observe gauge
reading:
Continued on next page
RG,35,JW7620
1920NOV971/3
13-397
