GMC 4000 Series Service Manual page 473

Sec. 8A
Page 462
FUEL TANK A N D EXHAUST
Figure 2 — Tube Flaring Tool J-8051
flap-type slit and trigger flow of fuel by forcing
air pressure through siphon towards container.
TANK REMOVAL
The following procedure is intended as a gen­
eral guide only and will vary according to truck
ser ie s and model.
1. Drain tank by removing drain plug (if equip­
ped) or using siphon as described previously.
2. Disconnect filler neck hose at lower clamp
as required to provide clearance for tank removal.
3. Disconnect fuel line(s) and wiring from tank
unit. Ignition switch must be in "OFF" position.
NOTE: On models when top of tank is not
readily accessible, loosen tank support straps
enough to disconnect tank unit wire.
4. Remove tank support straps and louver tank
from vehicle. To remove fuel tank sending unit,
refer to procedure under "Tank Unit Replacement"
described later in this section.
5. To install, reverse the ''Removal" proced­
ure. Replace all anti-squeak material and be sure
tank straps are positioned properly and tightened
evenly.
NOTE: When replacing polyethylene tank, tight­
en strap nuts securely with minimum bulging of
fuel tank.
Figure 3 — Sin gle a n d D ouble Lap Flare
G M C S E R V I C E M A N U A L
the ends of the tubing be flared properly for the
compression couplings. Unless the tubing is prop­
erly flared, the couplings will leak.
ends in order to produce a strong leak-proof joint.
with the proper size die block and upset flare
punch for each size tubing to form the double-lap
flare.
punches are as follows:
Tubing
Size
3/16"
1/4"
5/16"
Kit J-8051.
with a single-lap flare "A" and the other with a
double-lap flare "B." It will be noted that the
single-lap flare splits the tubing while the double­
lap flare shown in "B" is a heavy, well-formed
joint.
in making up fuel pipes:
(J-8000). Square off ends of tube and ream sharp
edges with reamer tool provided on the tube cutter.
and dip end of tubing to be flared in hydraulic
brake fluid. This lubrication results in better
formation of the flare.
One end of this punch is hollowed out to gauge the
amount of tubing necessary to form a double-lap
flare.
end toward the die blocks, install ram and tap
lightly until punch meets the die blocks and they
are forced securely against the stop plate (fig. 4).
Figure 4 — Flaring Operation IPositioning Tubing)
FUEL LINE INSTALLATION
In making up fuel lines, it is important that
The tubing must be double-lap flared at the
The Tool (J-8051) (fig. 2) must be equipped
The proper size die blocks and upset flare
Upset
Die Block Flare Punch
J-2185-27
J-2185-3
J-2185-37
J-2185-28
J-2185-29 J-2185-4
NOTE: These special tools are also part of
Figure 3 shows two pieces of tubing - one
The following procedure should be followed
1. Cut tubing to the desired length, using Tool
2. Install compression couplings on tubing
3. Select the correct size upset flare punch.
4. Slip the punch into the tool body with gauge
Finish
Flare Punch
J-2185-26
J-2185-26
J-2185-26