To boost fuel economy, auto makers switched from mechanical fuel pumps mounted on the engine block to electric fuel pumps, most often mounted inside fuel tanks. This boosted efficiency but made the process of replacing a defective pump more complicated, especially on early models, such as the 1988 Delta 88, since Oldsmobile didn't engineer an access hatch under the rear seat. The gasoline tank has to be removed to reach the fuel pump.
Tools Used: Socket wrench, Flat Screwdriver, Pliers, 2 hydraulic bottle jacks, 2 blocks of wood, 2 jack stands, Siphon hose, Gas cans, Digital camera, Fuel pump, Fuel pump gasket
Replace the Fuel Pump
Work Preparation
Chock the front wheels of the car to prevent it from rolling.
Jack-up the rear wheels of the car using hydraulic bottle jacks sufficiently high to allow you to work under the rear of the vehicle.
Place jack stands under the rear axle to support the vehicle. Remove the bottle jacks.
Disconnect the negative cable on the car's battery to disable the car's electrical system.
Siphon as much gasoline as possible from the gas tank into a portable gasoline container or containers.
Remove the Gas Tank
Position the two bottle jacks under the Delta 88's fuel tank, one towards the left side, the other towards the right side and in locations where they aren't obstructing access to the bolts which secure the tank to the vehicle's underside.
Place a small block of wood on each jack to increase the weight distribution on the jack when they are supporting the tank.
Lever each of the jacks upwards until the blocks of wood are firmly against the exterior of the fuel tank.
Remove the bolts securing the gasoline tank to the underside of the vehicle using a socket wrench.
Lower each of the jacks a little at a time, allowing the fuel tank to disengage and lower from its position under the vehicle. Keep lowering one after the other, incrementally, until you can see and access the rubber hoses and electrical wires attached to the upper side of the fuel tank.
Photograph the position of the wires with a digital camera as a reference to ensure they are reconnected to the proper locations when being reassembled.
Remove the wires by pulling on the connector ends where they attach to the old fuel pump.
Loosen the hose clamps holding the filler hose, the vent hose and the fuel line to the engine using a screwdriver or pliers.
Pull each of the hoses free of their connections.
Lower the jacks supporting the tank to their fully down position. The tank is now completely free from the vehicle and capable of being pulled out from under the car.
Change the Fuel Pump
Remove the screws around the perimeter of the top of the fuel pump to which the electrical wires and fuel delivery hose were attached. Use either a large, flat screwdriver or an appropriately-sized socket wrench since these screws have both a hexagonal head as well as slot for a screwdriver.
Lift the defunct fuel pump out of the tank. Remove the old fuel pump gasket.
Position the new fuel pump gasket on the top of the tank, insert the new fuel pump and secure the connecting screws firmly in place.
Finish the Job
Dump any remaining gasoline in the tank into a portable fuel canister to lighten the tank and facilitate re-installation.
Balance the empty gas tank on the bottle jacks and carefully raise the tank high enough to reconnect the filler, vent and fuel delivery hoses. Reconnect the electrical wires referring to the digital photo, if necessary.
Raise the tank all the way into position, replace the bolts which secure the tank to the vehicle.
Remove the jack stands, reconnect the negative battery cable to the vehicle's battery and the job is complete.
Tips & Warnings
The vehicle may start hard or run rough for a few seconds the first time you start the engine after changing the fuel pump. Some amount of air will have gotten into the fuel line. As soon as the air gets purged from the fuel system, normal starting and running should resume.
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