Do you have to drop the gas tank to replace the fuel pump on the 1990 model?

Yes...

EBSCO Auto Repair Reference Center

Electric Fuel Pump
REMOVAL & INSTALLATION

Fig. 1: The fuel pump locking ring can be removed using this tool




Fig. 2: The fuel pump and fuel gauge sender assembly




Fig. 3: The fuel pump locking ring can also be removed using a brass drift




Fig. 4: With the locking ring removed, the fuel pump (and/or gauge sender) can be lifted from the tank



NOTE: The following procedure requires the use of the GM Fuel Gauge Sending Unit Retaining Cam tool No. J–24187 or equivalent.

CAUTION
Before removing any component of the fuel system, be sure to reduce the fuel pressure in the system. The pressure regulator contains an orifice in the fuel system; when the engine is turned Off, the pressure in the system will bleed down within a few minutes.

If the fuel system has been in use, turn the ignition switch to OFF and allow the system time to reduce the fuel pressure.
Disconnect the negative battery terminal from the battery.
NOTE: Be sure to keep a Class B (dry chemical) fire extinguisher nearby.

CAUTION
Due to the possibility of fire or explosion, never drain or store gasoline in an open container.


Using a hand pump or a siphon hose, drain the gasoline into an approved container.
Raise and support the vehicle on jackstands.
Support the fuel tank and remove the fuel tank-to-vehicle straps.
Lower the tank slightly, then remove the sender unit wires, the hoses and the ground strap.
Remove the fuel tank from the vehicle.
Using the GM Fuel Gauge Sending Unit Retaining Cam tool No. J–24187 (or equivalent) or a brass drift and a hammer, remove the cam locking ring (fuel sending unit) counterclockwise, then lift the sending unit from the fuel tank.
Remove the fuel pump from the fuel sending unit, by performing the following procedures:
Pull the fuel pump up into the mounting tube, while pulling outward (away) from the bottom support.
NOTE: When removing the fuel pump from the sending unit, be careful not to damage the rubber insulator and the strainer.


When the pump assembly is clear of the bottom support, pull it out of the rubber connector.
To install:

Inspect the fuel pump hose and bottom sound insulator for signs of deterioration, then replace it, if necessary.
Push the fuel pump onto the sending tube.
Using a new sending unit-to-fuel tank O-ring, install the sending unit into the fuel tank.
NOTE: When installing the sending unit, be careful not to fold or twist the fuel strainer, for it will restrict the fuel flow.


Using the GM Fuel Gauge Sending Unit Retaining Cam tool No. J–24187 (or equivalent) or a brass drift and a hammer, turn the sending unit-to-fuel tank locking ring clockwise.
Install the fuel tank, align the insulator strips and install the strap bolts. Torque the inner fuel tank strap-to-vehicle bolts to 26 ft. lbs. (35 Nm) and the outer fuel tank strap-to-vehicle nuts/bolts to 26 ft. lbs. (35 Nm).
Attach the fuel lines, then connect the negative battery cable, start the engine and check for leaks.
Lower the vehicle.

EBSCO Auto Repair Reference Center