Pontiac Fiero 1988 Service Manual page 379

6C-8 FUEL SYSTEM
vacuum/pressure pump J-23738 to the tank
vapor line. Tee one hose from manometer
J-23951 into the tank vapor line between J-23738
and the tank. Vent the other manometer hose to
atmosphere.
3. Apply 15 in. Hg. pressure to the tank vapor line.
a. Check for excessive pressure loss - greater
than 3 in. Hg pressure in five minutes.
b. If excessive pressure loss occurs, check for
fuel vapor odor or fuel loss at areas specified
in Diagnosis.
c. Remove filler cap and check tank pressure.
4. With the fuel cap removed, use J-23738 to force
air through the vapor vent line to check for
restrictions.
ON CAR S E R V I C E
FUEL PRESSURE RELIEF PROCEDURE
CAUTION: To reduce the risk of fire
and personal injury, it is necessary to
relieve the fuel system pressure
before servicing any fuel system
components.
2.5LTBI ENGINE (LR8)
When repair to the system has been completed,
start the engine and check all connections that were
loosened for possible leaks.
1. Remove "fuel" pump fuse from fuse block
located in the passenger compartment.
2. Start engine and let run until engine stops
running due to lack of fuel.
3. Engage starter again for 3 seconds, to assure that
all pressure has been relieved from the system.
4. With ignition OFF replace fuel pump fuse.
Unless the procedure is followed before
servicing fuel line or connections, fuel
spray could occur .
2.8L-MPFI ENGINE (L44)
For MPFI fuel system pressure relief procedure,
see Section 6E3.
FUEL TANK
Draining Fuel Tank
NOTICE:
If a car is to be stored for any
appreciable length of time, the fuel should be
drained from the complete system, including EFI
unit and fuel pump, all fuel lines, and the fuel tank
in order to prevent gum formations and improper
engine performance.
1. Disconnect the negative battery cable. Also have
a dry chemical (Class B) fire extinguisher near the
work area.
2. Use a hand operated pump device when possible
to drain as much fuel through the filler tube as
possible.
3. If a hand operated pump device cannot be used
to complete the draining process, use a siphon at
the main (not return) fuel pipe at the fuel pump
or the fuel tank gage unit.
CAUTION: Never drain or store
gasoline in an open container due to
the possibility of fire or explosion.
4. Reinstall any removed hoses, lines and cap.
FUEL SYSTEM CLEANING PROCEDURE
CAUTION: This procedure will NOT
remove all fuel vapor. Do not attempt
any repair on tank or filler neck where
heat or flame is required, as an
explosion resulting in personal injury
could occur.
If trouble is due to contaminated fuel, or foreign
material that is in the tank, it can usually be cleaned.
If tank is rusted internally, it should be replaced.
1. Disconnect battery and engine harness connector
on HEI distributor. Have dry chemical (Class B)
fire extinguisher near the work area.
2. Relieve fuel system pressure (see "Fuel System
Pressure Relief").
3. Disconnect negative battery cable.
4. Drain fuel tank (see "Draining Fuel Tank").
5. Remove fuel tank (see "Fuel Tank Removal").
6. Remove external fuel filter and inspect for
contamination. If filter is plugged, replace.
7. Locate tank away from heat, flame or other
source of ignition. Remove fuel gage sending unit
and pump assembly, if so equipped, and inspect
condition of strainer. If strainer is contaminated,
a new strainer should be installed upon
reassembly.
8. Complete draining of tank by rocking it and
allowing fuel to run out of fuel meter/pump
assembly opening.
9. Purge fuel tank with running hot water for at
least five minutes. Pour water out of fuel meter
opening. (Rock tank to be sure that removal of
water is complete.)
10. Disconnect fuel feed pipe at the engine end and
use air pressure to clean fuel line. Apply air
pressure in the direction opposite fuel flow. On
vehicles equipped with a fuel return line, clean
line in similar manner. Disconnect pipe at engine
end and apply air pressure to clean return line.
Reconnect and torque all pipes to 26-34 N*m
(19-25 lb. ft.).
11. Use low air pressure to clean pipes on fuel gage
sending assembly unit.
12. Install new strainer on fuel meter/pump
assembly,if required. Install fuel gage sending
unit and pump with new gasket in tank, and
install fuel tank. Connect fuel gage wire harness
to body harness. Connect all fuel lines, except
feed line to external fuel filter.
13. Disconnect fuel feed hose to chassis pipe at rear.
Connect a hose to rear end of chassis fuel feed ^
pipe and insert other end of hose into a one gallon
fuel can.
14. Connect battery cable.