11. FUEL PUMP REPAIR AND TESTING
11.1 DISASSEMBLY (Fig. 36)
11.1.1
Disassembly is best done while holding the
pump body in a vise with regulator control
hoses removed.
11.1.2
11.1.3
11.1.4
11.1.5
11.1.6
11.1.7
11.1.8
11.1.9
11.1.16 Check all O-rings for damage.
11.2 ASSEMBLY (Fig. 36)
11.2.1
Pull pump lever pin (N) and remove pump
lever (P).
11.2.2
Remove locking screw (A) with 13mm
socket and pull off locking plate (B).
Remove locking nut (C) with 32mm socket
and carefully pull out element’s piston (D)
and spring (E).
Remove entire check valve assembly by
unscrewing locking screw (L) with 32mm
socket.
11.2.3
Remove regulator unit by removing three
locking screws (M).
Remove all regulator parts.
11.2.4
Take pump body out of vise. Turn pump
body upside down and bounce the body
on a piece of hardwood until pressure
piece (F) and cylinder element (H) drop
out.
11.2.5
Clean all parts thoroughly with an autho-
rized cleaning solvent.
11.2.6
11.1.l0 Check all parts for wear or damage as
follows:
Assemble and install regulator unit and
plug, and tighten locking screws (M) se-
curely with 13mm socket.
11.1.11 Check pump lever (P) for flat spots on face
of lever and for wear on lever’s nose.
11.3 BENCH TESTING THE PUMP
(Fig. 36)
11.1.12 Check pump lever pin (N) for wear. Re-
place if necessary.
11.3.1
Hook up hydraulic control lines and master
control (see Section 8.3).
11.1.13 Insert piston (D) into cylinder element (H).
Close bottom of cylinder element with the
palm of your hand and pull piston out. The
element should create obvious suction.
Check top of piston assembly for wear.
The pump element assembly must be re-
placed as a whole, since the piston (D) and
the cylinder (H) are a lapped set.
11.3.2
Place fully assembled pump upright into
vise, with pan below nozzle to catch fuel.
11.3.3
11.3.4
Connect one side of the pump to a diesel
fuel reservoir by means of the fuel line.
Connect second fuel line to other side of
pump. This line acts as a breather line, and
must return back to the reservoir.
11.1.14 Check buna cone (I) for damage or dirt in-
clusions on the sealing surface. Check
valve spring (K) for proper length. It should
be 40mm (1.57") long. If length ap-
proaches 38mm (1.5"), the spring has lost
tension and should be replaced.
11.1.15 Check whether valve body (J) moves freely
within the locking nut (L).
TM 5-3895-363-13&P
Make sure all parts, including pump body,
are absolutely clean. Assembly is best
done while holding the pump body in a
vise.
Place O-ring (G) over cylinder element (H).
Place pressure piece (F) over cylinder ele-
ment (H). Install pressure spring (E) and
piston element (D) into cylinder element
(H). Install complete assembly into pump
body. Be sure the inside of the pump body
is clean, since there is a metal to metal seal
between the cylinder (H) and the body.
Install locking nut (C) with 32mm socket
and tighten securely. Install locking plate
(B), and secure with locking screw (A)
using a 13mm socket.
Install pump lever (P) with pump lever pin
(N). Set cotter pin (O).
Install check valve assembly (L). Secure
buna cone (I) to valve body (J) with a drop
of petroleum jelly. Grease O-ring slightly
with petroleum jelly, and tighten locking
screw (L) securely with 32mm socket.
Operate the pump lever (P) slowly by hand
until no more air bubbles are visible in
either breather line or fuel line. Place a
7.2mm (9/32") thick washer over the top of
the piston assembly (D). This washer limits
the stroke to the actual conditions that
would exist were the pump mounted to the
machine.
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