GMC 1989 Light Duty Truck, Repair Manual, Page: 578 / 998

6C1-2 MODEL 1MEF CARBURETOR
CARBURETOR IDENTIFICATION
M odel N um ber: 17086101
A pplications: F e d e ra l ( N o n - C a lif o r n ia ) , a n d
Canada
4.8 Liter L6 engine
T h e c a r b u r e t o r i d e n t i f i c a t i o n n u m b e r is
stamped vertically on the float bowl, next to the fuel
in let nut (Figure 1). Refer to this n u m b e r w h e n
servicing the carburetor.
C arburetor parts are shown in the disassembled
view (Figure 9), and are identified by name on th e
facing page (Figure 10).
N O TIC E: T h e f a c t o r y - s e t m e t e r i n g r o d
a d j u s t i n g s c r e w
, l o c a t e d in t h e a i r h o r n
( F ig u r e 6 ) , c o n t r o l s t h e p o s i t i o n o f t h e
e n ric h m e n t p o r tio n o f th e m e te r in g ro d in th e
j e t A n y a t t e m p t to r e a d ju s t th is s c re w c o u ld
re s u lt in e n g in e d a m a g e o r excessive em issions.
Figure 1 - C arburetor Identification
B-06647
A. M odel N u m b e r
B. Day O f Year
C. S ou rce C ode
D. Year
E. A s s e m b ly P lant Code
F. S h ift Id e n tific a tio n
Figure 2 - M od el 1MEF C arburetor (Front V ie w )
F-01477
GENERAL DESCRIPTION
M o d e l 1 M EF is a sin gle stage, s in g le b a rre l
carburetor of the " 1 M " fa m ily (Figure 2). Letters
fo llo w in g the " 1 M " designate these features:
E: It has an integral Electric choke.
F:
It has a d ju sta b le w id e o pen th ro ttle m ix tu re
control.
M odel 1MEF has three major assemblies: an air
horn, a flo a t bowl and a throttle body. It has the six
operating systems shown in Figures 3 through 8:
Figure 3 Float Figure 6 Power
Figure 4 Idle Figure 7 Pump
Figure 5 M a in M eterin g Figure 8 Choke
IDLE STOP SOLENOID (ISS)
The electric idle stop so le n o id (ISS) is used to
provide the desired engine idle speed, and to prevent
"dieseling" w h e n the ignition is switched off.
UNIT REPAIR
The in f o r m a t i o n t h a t f o l l o w s a p p l i e s t o a
complete o ve rh a u l, after th e c a rb u re to r has been
removed from the engine, and includes disassembly,
thorough cleaning, inspection and replacem ent o f all
g a s k e ts , se a ls, w o r n o r d a m a g e d p a r t s , a n d
adjustment o f individual systems.
Refer to the disassembled view (Figure 9), and
parts list (Figure 10), for parts identification.