TRUCK SERVICE MANUAL
ENGINE
6. Variations in governor characteristics make small
Note: "No air" pressures are given in Fuel Pump
difference in maximum governed speed between
Calibration Manual. Check with a Cummins Distributor.
different engines.
Such variations are of small
importance In most applications.
13. Always make the above checks on a hot engine.
Note:
Injectors must be adjusted to proper
Check Aneroid Adjustment
specifications before fuel manifold pressure readings.
Normally, no adjustment of the aneroid is required,
however, if smoke is evident and all other engine
7. Check maximum fuel manifold pressure with ST-
adjustments have been checked, back out adjusting
435. Fig. 2-64. Remove 1/8 inch pipe plug from side of
screw (4, Fig. 2-65). If screw must be backed out until
fuel shut-off valve on top of fuel pump. Connect the
acceleration is slow, have unit checked by a Cummins
gauge line in pipe plug hole.
Distributor.
Note: If smoke is excessive after 15 seconds of full
throttle operation, aneroid is not at fault, have fuel
system and turbocharger checked.
If, during Fuel Manifold Pressure Check, it is determined
that aneroid bellows should be replaced,
Check Turbocharger Bearing Clearance
Check bearing clearances every "C" Check; refer to "D"
Check.
Change Aneroid Oil And Replace Breather
At each "C" Check, remove fill plug and drain plug ,
Fig. 2-64, (N11966) Checking fuel manifold pressure
allow aneroid to drain. Replace drain plug , fill aneroid
with ST-435
with clean engine lubricating oil. Replace fill plug.
8. Remove linkage from the throttle lever. This will
Remove and replace aneroid breather Tighten breather
allow throttle to be operated by hand.
to 10 to 13 ft-lbs [15 to 18 No m] torque.
Caution:
On turbocharged engines with aneroids,
'D" MAINTENANCE CHECKS
temporarily disconnect aneroid, inlet line and plug hole,
At each "D" Maintenance Check, perform all "A", "B" and
to reach maximum fuel pressure during the short
"C" Checks in addition to those following.
acceleration period.
Clean And Calibrate Injectors
9. Start the engine. Run long enough to purge air from
Clean and calibrate injectors regularly to prevent
the pump. Loosen the gauge end of pressure line and
restriction of fuel delivery to combustion chambers. To
bleed air from line.
clean and calibrate injectors refer to FUEL SYSTEM,
Injectors, Calibration Instructions.
10. Watch gauge closely and snap throttle fully open.
The gauge hand will hit a maximum value, then
Replace Fuel Pump Screen And Magnet
immediately drop back as the governor takes control.
PT (type G) Fuel Pump
1. Loosen and remove cap, remove "O" ring and
11. Compare the maximum value with previous readings
spring.
taken to determine if fuel readings are satisfactory.
2. Lift out filter screen assembly. Discard screen
Normally this check is only taken if there is a suspected
assembly.
loss of power.
3. Install new filter screen assembly in fuel pump with
hole down, position spring on top of filter screen
12. Remove plug and reconnect aneroid to fuel pump,
assembly.
remove air line from intake manifold to aneroid and
4. Replace cap and "O" ring; tighten to 8 to 12 ft-lbs [11
check "no air" pressure.
to 16 Nm] torque.
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