Chevrolet 10 1971 Series Chassis Service Manual page 325

Fuel Tanks and Attachments .................................................................
Fuel L i n e s ....................................................................................................
Evaporation Control System (ECS) C o m p o n e n ts ...............................
General Description ...................................................................................
Component Part Replacement
Draining Fuel Tank ............................................................................
All cab model truck have fuel tanks mounted behind the
seat within the cab. The tank is constructed of two steel
sections, seam welded, together. The filler neck extends
through the left side of the cab, at a convenient height
from the ground. Exceptional stiffness is secured by the
combination of the welded flanges and depressed ribs in
both the front and rear halves. The tank is bolted to the
rear of the cab and to the floor panel.
On 1 ton forward control models and cowl models, the
tank is mounted on the outside of the left frame side rail.
A strong mounting of two metal straps anchor these tanks
to mounting brackets which are bolted to the frame side
member.
On 1/2 and 3/4 ton conventional and 4-wheel drive
models, Suburban and Blazer, the tank is located to the
rear of the axle and between the side rails and envelopes
the forward edge of the spare tire. These tanks are sup­
ported by one or two steel straps which are held at either
end by a hook into the side rail. Metal to metal contact
between tank and brackets or straps is prevented by the
use of anti-squeak material.
Upper and lower filler necks vary as to size, length
and shape, depending on model requirements. Th'ese
necks are treated so that rust will not form and get into
the fuel system. Lower filler necks are first bolted or
riveted to the tank, except on cab models, and then sweat
soldered in place to eliminate any possibility of leakage
at this point.
All tanks (10 series) are equipped with a pressure-
vacuum filler neckcaps.
The fuel pickup pipe is built integrally with the tank
gauge unit, located at the top of the tank. A large area,
fine-mesh screen is located on the bottom of the fuel
pickup pipe. This screen is designed to prevent the
SECTION 8
FUEL TANK AND EXHAUST
CONTENTS OF THIS SECTION
FUEL TANKS AND ATTACHMENTS
..............................................................
GENERAL DESCRIPTION
Page
8-1 Exhaust Systems ...................................................................................... 8-11
8-5 Special Tools ............................................................................................. 8-15
8-8
INDEX
Page
8-1 Fuel Tanks .............................................................................................
8-2 Metering Units (Gauge Sending Unit)
8-2 Cleaning Fuel Systems
entrance of dirt or water into the fuel system, and oper­
ates with a self-cleaning action.
Frame mounted tanks consist of an upper and lower
half, each with a wide flange. The two tank sections are
seam welded at the flange around the entire tank to as­
sure leakproof construction. Exceptional stiffness is
secured by the combination of the welded flanges and
depressed ribs in both upper and lower tank sections.
Evaporation Control System (ECS)
1971 Evaporation Control System (ECS) is standard
equipment under federal regulations for all truck series
rated under 6,000 pounds maximum obtainable GVW.
Consequently, all fuel tanks, formerly RPO NA9, are
now standard equipment. Important changes have been
made to improve performance and increase reliability.
The most noteworthy being in the area of fuel fill. Past
versions used partial inner tanks as fuel fill limiter
devices. Current designs use filler necks extended fur­
ther into the fuel tank and a revised fill vent tube.
Tank Filler Neck Gas Cap— 10 Series Only
The 10 series truck fuel tank filler cap has a pressure-
vacuum safety relief valve.
If this 10 series truck gas cap re­
NOTE:
quires replacement, only a cap identified on the
inside of the cap with "pressure-vacuum" should
be used. Failure to use the correct cap can re­
sult in a serious malfunction of the system.
Correct replacement caps may be obtained from
your Chevrolet dealer.
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10-30 CHEVROLET TRUCK SERVICE MANUAL
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Page
8-3
8-3
8-5