GMC 4000 Series Service Manual page 383

Sec. 6M
Page 372
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
Figure 2 9 — Installing Fuel Delivery Valve
Retainer with Torque Wrench
and a brush to remove any accumulated dirt from
top of the injection pump assembly. Wash off top of
head assembly and blow dry with com pressed air.
2. Remove delivery valve cap and gasket, then
use a 12-point socket to remove the delivery valve
retainer from the head assembly.
3. Remove the delivery valve spring, then use
needle-nose pliers or tweezers to remove the
valve assem bly and gaskets.
INSPECTION (Fig. 28)
1. Inspect spring for breakage at tips and re­
place if necessary.
2. Inspect valve and valve seat for pitting,
corrosion, and scoring. Replace if damaged.
3. Replace all gaskets and damaged parts.
INSTALLATION (Fig. 28)
IMPORTANT: The delivery valve and retaining
parts must be kept absolutely clean during install­
ation. Any particles of dirt entering the delivery
Figure 3 0 — Fuel Control Unit A sse m b ly
G M C S E R V I C E M A N U A L
valve cavity in the hydraulic head will be carried
by fuel to plunger area and to fuel injection noz­
zles. Extensive damage to pump and/or nozzles
can result from presence of foreign particles in
fuel.
kets in position in hydraulic head cavity (fig. 32),
then position the delivery valve spring over pilot
on the delivery valve.
a torque wrench to tighten valve retainer to 65 to
70 foot-pounds torque.
valve retainer, then install the delivery valve cap
nut and tighten to 55 to 60 foot-pounds torque.
ring seal (fig. 30), the procedure given below must
be followed to remove and install the fuel control
unit assembly.
REMOVAL
access to control unit cover at right side of the
fuel injection pump.
ing screw s, then remove cover and gasket.
shown in figure 31, so parts cannot fall into pump
interior as they are removed.
Figure 31 — Control Unit Retaining Parts
Removed Sh o w ing A lignm ent M arks
1. Place fuel delivery valve assembly and gas­
2. Install the delivery valve retainer and use
3. Position the cap nut gasket on the delivery
CONTROL UNIT ASSEMBLY
REPLACEMENT
In case it becomes necessary to replace O-
1. Remove any equipment necessary to gain
2. Remove the four control unit cover attach­
3. Place a clean lint-free cloth in opening as