GMC S Series 1994, Repair Manual

Page: 570 / 919

THROTTLE BODY DISASSEMBLY
IDLE AIR CONTROL (IA C ) VALVE
N O T IC E : T h e I A C v a lv e is a n e l e c t r i c a l c o m ­
p o n e n t a n d m u s t n o t b e s o a k e d in a n y liq u id
c l e a n e r o r s o l v e n t a s d a m a g e m a y r e s u lt.
Important
All IAC valves on TBI Model 220 units (except those
on the 7.4L engine) are thread-mounted and have a
dual-taper pintle. On the 7.4L engine, the IAC valve is
flange-m ounted and has a dual-tape r pintle. Any
replacement of an IAC valve must have the correct part
number, with the appropriate pintle taper, for proper
seating of the valve in the throttle body.
Remove or Disconnect (Figure 2)
1. IAC valve.
• On thread mounted units, use a 32-mm (1
1/4-inch) wrench.
• On flange-mounted units, remove screw assem­
blies.
2. IAC valve gasket or O-ring and discard.
TH R O TTLE PO SITIO N SENSOR
(TP SENSOR)
N O T IC E : T h e T P s e n s o r is a n e l e c t r i c a l c o m ­
p o n e n t a n d m u s t n o t b e s o a k e d in a n y liq u id
c l e a n e r o r s o l v e n t a s d a m a g e m a y r e s u lt.
Important
On the model 220 TBI unit, the TP sensor is throttle
shaft driven and non-adjustable. Make sure to order the
correct TP sensor with the identical part number for the
engine if replacement is necessary.
E3
Remove or Disconnect (Figure 2)
1. Two TP sensor attaching screw assemblies.
2. TP sensor from throttle body assembly.
3. TP sensor seal.
IDLE SPEED CO NTROL (ISC)
ACTUATOR ASSEMBLY
(7.4 L ENG INE ONLY)
Remove or Disconnect (Figure 2)
1. Two ISC actuator assembly attaching screws.
2. ISC actuator from the throttle body assembly.
FUEL METER COVER
The fuel meter cover assembly contains the fuel pres­
sure regulator assembly. The regulator has been adjust­
ed at the factory and should only be serviced as a
complete preset assembly.
CAUTION: DO NOT remove the four screws
securing the pressure regulator to the fuel
m eter cover. The fuel pressu re regulator
includes a large spring under heavy com­
pressio n w h ich , if a c c id e n ta lly release d ,
could cause personal injury. Disassem bly
might also result in a fuel leak between the
diaphragm and the regulator container.
Remove or Disconnect (Figure 2)
1. Long and short fuel meter cover screw assemblies.
2. Fuel meter cover assembly.
N O T IC E : D O N O T i m m e r s e t h e f u e l m e t e r
c o v e r ( w it h p r e s s u r e r e g u la t o r ) in c le a n e r , a s
d a m a g e to t h e r e g u l a t o r d ia p h r a g m a n d g a s ­
k e t c o u l d o c c u r .
3. Fuel meter outlet gasket. Discard gasket.
FUEL INJECTO RS
Each fuel injector is serviced as a complete assembly
only (figure 2).
N O T IC E : U s e c a r e in r e m o v in g t h e f u e l in j e c ­
to r s to p r e v e n t d a m a g e to t h e e l e c t r i c a l c o n ­
n e c t o r t e r m in a ls , t h e i n j e c t o r f ilte r , a n d t h e
f u e l n o z z le . T h e f u e l i n j e c t o r is s e r v ic e d a s a
c o m p l e t e a s s e m b l y o n ly . A l s o , s i n c e t h e
i n j e c t o r s a r e e l e c t r i c a l c o m p o n e n t s , t h e y
s h o u l d n o t b e i m m e r s e d in a n y t y p e o f liq u id
s o l v e n t o r c l e a n e r s i n c e d a m a g e m a y o c c u r .
+-► Remove or Disconnect (Figure 2 and 3)
• With fuel meter cover gasket in place to prevent
damage to casting, use a screwdriver and fulcrum
to carefully lift out each injector (figure 3).
A. FULCRUM
B. SCREWDRIVER
5. GASKET, FUEL METER COVER
7. INJECTOR ASSY, TBI FUEL
3706r4809