How to Fix the Fuel Pump on a 1989 Chevy S-10

The 1989 Chevrolet S-10 was available with two-wheel and four-wheel drive drivetrains. The base engine for the 1989 Chevrolet S-10 two-wheel drive was a 2.5-liter L4 TBI engine. A 2.8-liter TBI V-6 and 4.3-liter TBI V-6 were available for the 1989 S-10 as well. The fuel pump on the 1989 S-10 is attached to the fuel pump sending unit. You can replace the fuel pump from the existing sending unit for less money than an entire fuel pump and sending unit would cost together. Replacing the entire assembly as a whole is less time consuming.

Instructions

Park the S-10 on a solid level surface. Remove the ignition key from the ignition. Open the hood of the S-10. Proceed to the front of the truck. Remove the negative battery cable from the battery terminal, using a ratchet and socket. Tuck the cable to the side of the battery, so there is no chance of accidental contact during this project.

Position yourself at the driver's front side of the truck. Remove the protective cap from the fuel pressure testing valve, located on the upper lip of the left front fender. Place a rag over the headlight wiring bundles to protect them. Wrap a rag around the tip of a screwdriver. Depress the center of the fuel pressure testing Schrader valve, and release the fuel pressure from the fuel system. Allow the rag on the screwdriver to absorb any expelled fuel. Release the valve stem when the fuel pressure is completely let out. Install the protective cap on the tester port.

Place wheel chocks in front of the front two tires. Move to the rear of the truck. Raise the rear of the S-10, using a 2-ton or greater capacity floor jack. Place jack stands beneath both ends of the rear axle housing, as close to the rear wheels as possible. The wider apart the jack stands are, the lower your center of gravity and more stability your stands will have. Lower the truck onto the jack stands.

Lie beneath driver's rear fender. Position yourself to access the two hoses extending from the tank to the filler neck. Remove the hose clamps from both hoses, using a ratchet and socket. Disconnect the rubber filler hose and vapor hose from the filler neck and vapor tube. Use a flat-head screwdriver to gently pry the hoses free if needed. Move to the rear of the truck and lie beneath the rear bumper once the two fuel hoses are disconnected.

Position yourself beneath the fuel tank to access the forward and rearward fuel tank straps. Place your jack directly beneath the tank, and place your 1-foot long plank of wood on top of the jack. Raise the jack to the bottom of the fuel tank, but do not push up on the bottom of the tank. Remove the rearward tank strap bolt closest to the center of the truck, using a ratchet and socket. Move the strap downward and to the rear of the truck.

Remove the forward strap bolt from the driver's side chassis rail, near the fender. This strap wraps completely around the fuel tank, and may just need to be loosened, rather than removed. Use a ratchet and socket to loosen or remove the strap bolt enough to free the fuel tank. Lower the fuel tank halfway between the bottom of the truck and the ground. Remove the electrical connector from the top-mounted fuel pump by hand. Remove the three hose clamps from the fuel pump and remove the three smaller hoses from the pump. Remove the fuel pump ground strap.

Lower the fuel tank down completely on the jack. Transfer the fuel tank from your jack and plank to a large piece of cardboard. Slide the fuel tank out from beneath the rear of the truck, keeping the tank on top of the cardboard. The cardboard is essential to avoid sparks between the ground and the fuel tank while moving the tank.

Place the tip of your flat-head screwdriver against the upward facing tab of the fuel pump lock ring, or cam lock. Tap the handle of the screwdriver to rotate the cam lock counterclockwise, until the fuel pump springs upward and the cam lock is released. Remove the lock ring from the fuel pump assembly.

Push the fuel pump back down into the tank and make a mark from the top of the tank across the top of the fuel pump sending unit assembly, using a white crayon. Remove the fuel pump and sending unit, and transfer the assembly directly to a drain pan. Make sure your large O-ring pump gasket does not fall into the fuel tank.

Proceed to Section 2 of this project if you are going to replace the fuel pump within the existing sending unit. If you are replacing the fuel pump and sending unit as one assembly, proceed to Step 11 of this section.

Hold your new fuel pump and sending unit near the old pump. Rotate the head of the new pump to align it in the same direction as the old pump. Copy the white line on top of the new pump sending unit, in the same position it is on top of the old pump sending unit. This is your positioning guide for proper insertion into the fuel tank. Place a new o-ring gasket around the fuel tank sending unit, by sliding the gasket upward from the bottom of the entire assembly.

Place the new fuel pump into the fuel tank, eyeballing the alignment of the white mark on the tank with the one on the new pump sending unit. Push the new fuel pump assembly downward into the fuel tank. Install the cam lock over the new pump assembly. Turn the cam lock clockwise by hand to set the primary position of the new pump assembly. Insert your flat-head screwdriver against the cam lock and tap the handle with a hammer to rotate the lock clockwise until the cam lock is completely locked into the fuel tank.

Move the fuel tank beneath the truck, keeping the cardboard beneath the tank. Transfer the fuel tank onto your plank of wood that is on top of your jack. Raise the fuel tank about halfway between the ground and the bottom of the truck. Angle the forward end of the tank upward to set it inside the forward tank strap assembly. Install the three small fuel tubes to the new fuel pump and tighten the clamps snug with your ratchet and socket. Install the electrical connector on to the new pump assembly by hand.

Install the fuel pump ground strap back onto the truck and tighten the bolt snug with a ratchet and socket. Lift the fuel tank completely to the bottom of the truck, but do not push upward on the tank once it rests against the truck.

Set your rearward fuel tank strap around the tank. Install the fuel tank strap bolt onto the frame of the truck. Install the forward tank strap nut onto the strap if you removed it. Tighten the rearward strap to 18 foot-pounds of torque, using a 1/2-inch-drive torque wrench and socket. Tighten the forward tank strap nut to 5 foot-pounds. Lower the jack and remove the jack and plank of wood from beneath the S-10.

Move to the driver's side of the truck. Install the rubber fuel tubes back onto the metal vapor neck and fuel filler neck. Tighten the hose clamps snug with your ratchet and socket.

Raise the S-10 off of the jack stands, then remove the stands from beneath the truck. Lower the truck to the ground. Proceed to the front of the truck. Connect the negative battery cable to the battery and tighten the battery cable snug with your ratchet and socket.

Open the driver's door of the S-10. Insert and turn the ignition key to the "II" accessories position without starting the engine. Turn the key back to the "Off" position. Repeat the key motion to accessories then back off, three times. Listen for the humming sound of the fuel pump as it primes the fuel system with fuel and pressure. If you hear any hissing noises, stop and remove the ignition key. Inspect the system for leaks and repair as needed. Start the engine of the truck after priming if no leaks are detected.

Pull the fuel pump upward into the fuel sending unit, away from the bottom support. Maneuver the pump out of the way of the bottom support.

Pull the old fuel pump free from the small rubber tube, being careful not to damage the tube. Remove the small hose clamp from the rubber tube with needle-nose pliers, if equipped. Set the old fuel pump directly into a drain pan.

Install a new fuel strainer onto the new fuel pump if a strainer is not already installed. Simply snap the strainer onto the bottom of the new pump by hand. Install the new pump and strainer onto the rubber hose connected to the sending unit, by hand. Place the small hose clamp back over the hose and fuel pump nipple if equipped, using needle-nose pliers. Carefully maneuver the pump back into the sending unit and allow the pump to rest against the bottom support of the unit.

Proceed to Step 11 of Section 1 of this project to continue with the installation of your fuel pump and sending unit back onto the truck.