Fuel pump/sending unit assembly is corroded and won't turn. What should I do? I am changing the fuel pump on a 2000 chevy blazer 4 door w/ 4 wheel drive.

1. Release fuel system pressure as outlined under Fuel Pressure Relief Hopefully may database is correct, just make sure fuel pump is the problem and not something else. 2. Raise and support vehicle. 3. Remove any skid shields. 4. Drain fuel from tank into an approved safety container, then support fuel tank with suitable lifting device. 5. Remove fuel tank support straps, then lower tank sufficiently to access fuel and electrical connections. 6. Disconnect fuel, vapor and electrical connections, then lower the tank. 7. Using cam lock wrench tool No. J-39765, or equivalent, rotate pump cam lock ring counterclockwise and remove fuel level sending unit and pump assembly. Discard O-ring. 8. Note strainer position and orientation, then remove and discard strainer. 9. Remove pump from sending unit, using caution not to damage rubber insulator. 10. Reverse procedure to install, noting the following: a. Ensure new strainer is properly positioned as noted during removal. b. Always replace sending unit O-ring with a new one.

You must remove the fuel tank which is underneath the trunk. Here's the procedure for removing the pump.

REMOVAL:

1. Before servicing the fuel pump the fuel system pressure must be relieved.
2. Disconnect the negative battery cable.
3. Raise the car on a hoist.
4. Remove the fuel tank.
5. Remove the fuel tank sending unit and pump assembly by turning the cam lock ring counterclockwise. Lift assembly from the fuel tank.
6. Pull the fuel pump up into the attaching hose while pulling outward away from the bottom support. Take care to prevent damage to the rubber insulator and strainer during removal. After the pump assembly is clear of the bottom support, pull the pump assembly out of the rubber connector for removal.

NOTE: Inspect the fuel pump attaching hose for any signs of deterioration. Also check the rubber sound insulator at the bottom of the pump. Replace damaged or deteriorated parts.

INSTALLATION:

1. Push the fuel pump assembly into the attaching hose.
2. Position the fuel tank sending unit and pump assembly into the fuel tank. Use a new "O" ring seal.

NOTE: Care should be taken not to fold over or twist the strainer when installing the sending unit as this will restrict the flow of fuel. Also, verify that the strainer does not block the full travel of the float arm.

3. Install cam lock over the assembly and lock by turning clockwise.
4. Reinstall fuel tank.

Fuel injectors ? Are there being commanded on by the PCM/ECM ? Do you know how to test fuel system , fuel pump relay etc... Fuel pressure test ! Follow this guy's testing procedure ! GM Fuel Pump Relay Testing If you can't your best bet is take to the dealer !

no, they are different pressure. it has to come from one with central fuel injection, like maybe 94 and up. also, the sending units even then

Park your car in a safe and level place and open the hood.
Relieve the fuel system pressure: On 1995-1997 2.2L engine models, remove the fuel-pump relay from the fuse block located in the engine compartment, then start the engine and let it stall. On other models, wrap a shop rag around the Schrader valve located on the inlet fuel line of the fuel rail, right before the first fuel injector--the valve is similar to an air valve on a bicycle tire. Depress the small stem inside the valve using a small standard screwdriver to free the fuel from the line Disconnect the black, negative battery cable
Raise the rear of the vehicle using a floor jack and safely support it on two jack stands.

• Disconnect the filler hose form the tank by removing the hose clamp using a Phillips screwdriver or ratchet and socket. Remove the fuel tank shield using a ratchet and socket
• Support the fuel tank with the floor jack and remove the tank-mounting straps using a ratchet, ratchet extension and socket.
  
• Lower the tank carefully, just enough to disconnect the two fuel hoses and vapor hose from the sending unit/pump assembly on top of the fuel tank
  
• Press the lock tabs on the hoses connectors, and pull the hoses from the assembly fittings. Unplug the fuel-pump electrical connector and lower the tank to the floor.
  
• Remove the lock ring from the sending unit/pump assembly using a drift punch and hammer. Carefully rotate the lock ring tabs counterclockwise with the drift punch and hammer until the ring is free from the assembly.
  
• Lift the sending unit/pump assembly off the tank and out of the vehicle.
  

Install Fuel Pump

• Make sure the pump filter is in a horizontal position and does not interfere with the movement of the sending unit float arm, then install the sending unit/pump assembly into the tank using a new O-ring between the assembly and the tank.
  
• Secure the assembly by turning the locking ring clockwise with the drift punch and hammer.
  
• Raise the fuel tank enough to connect the fuel and vapor hoses and plug the pump electrical connector.
  
• Install the tank-mounting straps and tank shield, and connect the filler hose to the tank
  
• Lower the vehicle and install the fuel-pump relay.
  
• Connect the black, negative battery cableStart the engine and check for fuel leaks.
  

WARNING
When replacing the fuel pump in your Chevy Blazer, safety is your most important factor. Do not allow smoking near or around the car, and park away from appliances with open flames, such as water heaters and dryers.

Have someone sit inside and turn key on, the fuel pump in the fuel tank should make a humming noise for a few seconds then shut off (primes the fuel system) until you start cranking.

Changing the fuel pump involves removing the fuel tank and then removing the fuel pump/sending unit from the tank, you do this by turning the retaining ring on the tank whic will have 3 to 4 tabs that stick up slightly. Tap of thos tabs lightly counterclockwise to remove the ring (if it is rusted, spray it with a good penetrating lubricant prior to attempting removal) Once the ring is remove the pump assembly will come out of the top of the tank, it's usually best to replace the pump and screen at the same time and can be purchased together in a kit from your local parts store.

The fuel pump and sending unit are in the same assembly. You will need to check the ground, a loose or corroded connection at the ground connection can cause all kinds of problems. If you end up taking the fuel pump assembly out, you can bench test the sending unit using an ohmmeter. Connect the lead to the ground connection and to the sending unit connection, move the float up and down and see that you have a good steady resistance change in both directions. If you have areas that are not reading then it is time to change the assembly out.

Relieve the fuel system pressure if any. Wrap a shop rag around the Schrader valve located on the inlet fuel line of the fuel rail, right before the first fuel injector-the valve is similar to an air valve on a bicycle tire; then depress the small stem inside the valve using a small standard screwdriver to free the fuel form the line.

1. Disconnect the black, negative battery cable; raise the rear of the vehicle using a floor jack and safely support it on 2 jack stands.
   
2. Working from underneath the vehicle, disconnect the filler hose form the tank by removing the hose clamp using a Phillips screwdriver or ratchet and socket; then remove the Fuel tank shield using a ratchet and socket. Support the fuel tank with the floor jack and remove the tank mounting straps using a ratchet, ratchet extension and socket.

Lower the tank carefully, just enough to disconnect the two fuel hoses and vapor hose from the sending unit/pump assembly on top of the fuel tank. Press the lock tabs on the hoses connectors and pull the hoses form the assembly fittings; unplug the fuel pump electrical connector and lower the tank to the floor.

Remove the lock ring from the sending unit/pump assembly using a drift punch and hammer. Carefully rotate the lock ring tabs counterclockwise with the drift punch and hammer until the ring is free from the assembly. Lift the sending unit/pump assembly off the tank and out of the vehicle.

Install the new pump on the sending unit/pump assembly. Make sure the pump filter is in a horizontal position and does not interfere with the travel movement of the sending unit float arm; then install the sending unit/pump assembly into the tank using a new O-ring between the assembly and the tank.

Secure the assembly in place by turning the locking ring clockwise using the drift punch and hammer; then raise the fuel tank enough to connect the fuel and vapor hoses and plug the pump electrical connector.

Raise the fuel tank, install the tank mounting straps and tank shield; connect the filler hose to the tank and lower the vehicle; install the fuel pump relay and connect the black, negative battery cable. Start the engine and check for fuel leaks.

Good luck and hope this helps. It's about a 4 hour job from start to finish, also if your going to go through all that work. Buy a wire harness from the fuel sending unit to the frame. It's only around $15.00 and who knows, it may just be a bad wire harness that may be the problem.

sending unit on the fuel pump in the tank is stuck, and needs to be replaced. its expensive, but that will fix your issue. its the housing around the pump that has the float arm on it. you can try to free the float arm by removing your pump assembly, but cant guarantee its any good after being stuck