Onan MEP-003A - Page 50

TM5-6115-585-34
NAVFAC P - 8-282-12
TO -
35C2-3-455-2
TM - 05684C - 34
CHAPTER
4
MAINTENANCE OF FUEL SYSTEM
Section 1. DESCRIPTION AND FUNCTION
4-1
.
GENERAL
.
The
engin
fuel
system
consists
of
two
pressure
systems
;
the
low
pressure
system
and
the
high
pres
sure
system
.
In
the
low
pressure
system
,
a
fuel
pump
may
draw
fuel
from
an
external
source
to
fill
set
tank
or
set
tank
may
be
filled
manually
.
If
an
exter
nal
fuel
source
is
selected
,
a
float
valve
assembly
in
the
set
tank
maintains
the
fuel
level
in
the
tank
.
Two
other
fuel
pumps
(
in
series
)
draw
fuel
from
the
set
tank
and
force
the
fuel
through
a
primary
strainer
,
two
secondary
filters
,
and
a
check
valve
assembly
,
to
the
injection
pump
.
In
the
high
pressure
system
,
the
fuel
injection
pump
forces
the
fuel
,
under
high
pressure , to the fuel injection nozzles . The injection
nozzles provide fuel to each combustion chamber of
the engine . A small quantity of unused fuel is re
turned from the
injectors
and
injector
pump to the
fuel tank . A cam and gear on the camshaft drives the
fuel injection pump . The gear drives the pump face
gear , providing fuel distribution to each cylinder in
the proper order . The cam operates the pump plunger ,
pressurizing fuel to the nozzles . A control sleeve
meters fuel by controlling the length of time the
plunger spill port is closed , maintaining pressure ,
and therefore , the amount of fuel delivered in each
stroke . The pintle type injection nozzles are conven
tional inward opening with adjustable opening pressure .
They are factory adjusted to open at 1900 to 1950 psi .
Section II . MAINTENANCE OF FUEL TANK
4-2
. FUEL
TANK
.
( 1 ) Repair leaks in fuel tank by soldering .
a . Inspect . Inspect the fuel tank per Operator / and
Organizational Maintenance Manual .
( 2 ) Clean repaired area with dry cleaning solvent
Federal Specification P - D - 680 .
b
.
Remove
.
Remove
fuel
tank
and
remove
com
ponents
per
Operator
and
Organizational
Maintenance
Manual
.
( 3) Paint as required with MIL - T - 704 , type A ,
semigloss , olive drab , color no . 24087 .
c . Test . Plug all but one opening in the fuel tank .
Connect a regulated low pressure air supply to tank
opening . Apply 3/4 to 1-1 / 4 psi to tank and submerge
tank into water . Check for leaks .
e
.
Install
.
d . Repair
.
WARNINO
( 1 ) Install the fuel tank and components per
Operator and Organizational Maintenance Manual .
Observe
all
safety
precautions
when
solder
ing
fuel
tank
.
Avoid
breathing
fumes
generated
by
lead
soldering
.
Eye
protection
is
required
.
( 2 ) Fill tank with fuel oil .
Change
3
4.1
/
(
4-2
blank
)