Replaced fuel pump motor on fuel pump assembly, reinstalled, have voltage to each of two connectors, but no pump action

I agree with Thomas, no shut off switch. There a couple of fuses relating to fuel pump relay, that you can check, one is hot all the time and the other goes hot with key on. Not only check the fuse, use a test lite and check voltage on fuse circuit.
At the fuel pump connector, green wire is voltage and black is ground, need both. If good voltage and ground with no fuel pump action, suspect the fuel pump. Are you missing anything else, like spark, where applicable? Any applicable trouble codes?

This is wiring for 2.5 and 4.0L engine, fuel pump. You can see wire colors, at the pump motor, top wire is voltage, bottom wire is ground. If voltage and ground is good and no pump action, suspect the fuel pump, check with engine cranking. Let the starter motor cool a little between cranking. Battery has a full charge and connections all good? Are you missing anything besides fuel? Engine cranking you have spark at the plugs and fuel injector pulse? Can you check for any applicable trouble codes?

There isn't one. I don't know what testing you have done? Did you check fuel pump connector for voltage and ground? Gray wire should be voltage, black wire is ground, check with engine cranking. If good voltage and ground with no pump action, suspect the pump. Could be other issues? Any applicable trouble codes?

Are you missing anything else, besides gas? Engine cranking, did you check for spark at the plugs and fuel injector pulse? Any applicable trouble codes? Did you check voltage and ground to fuel pump motor, before replacing anything?

I have to ask. How long since a tune-up? Are there any applicable trouble codes?
With engine cranking, if no spark at the spark plugs and no fuel injector pulse along with no fuel pump action, have to check rpm signal.
If you have spark and fuel injector pulse but, no fuel pump action, then we check the fuel pump circuit. Did you check applicable fuse, not only check the fuse, check the fuse circuit for voltage. At the fuel pump connector, gray wire is voltage for fuel pump motor and black wire is ground.

the two thick wires are for the pump and the other two for the fuel gauge ,check for voltage at the pump if no voltage then follow the wires back to see if their is a connection somewhere ,also check the earth connection if no power in the two wires ,ie one probe onto the earth and the other to a suitable ground on the bodywork ,then continuety

check for good ground from the pump wiring with a continuity tester with the battery dis-connected from the car

These units are in the tank and must be dropped in order to replace.


WARNING Do not handle the fuel sender assembly by the fuel pipes. The amount of leverage generated by handling the fuel pipes could damage the joints.

1. Relieve the fuel system fuel pressure, as outlined in the Fuel System Section.
2. Drain the fuel tank to at most 3/4 of a tank full.
3. Raise the vehicle.
4. Remove the fuel tank.
   NOTE The modular fuel sender support assembly will spring-up when the locking ring is moved.
   
5. Remove the fuel sender assembly using tool J39765 Fuel Sender Locknut Wrench or an equivalent.
6. Note the position of the fuel sender strainer for installation.
7. Support the reservoir with one hand and grasp the fuel sender strainer with the other hand.
8. Pull the external fuel sender strainer off of the fuel sender.
9. Inspect the fuel sender strainer. If the fuel sender strainer is contaminated, the fuel tank should be cleaned.
10. Discard the fuel sender strainer after inspection.
11. Disassemble the electrical connectors from the fuel level sensor assembly of the fuel pump and cover assembly.
12. Disassemble the fuel level sensor assembly.
    
    

    Fig. Fuel level sending unit on fuel sender (fuel pump) module.
    

To install:

1. Assemble the fuel level sensor assembly.
2. Assemble the electrical connectors to the fuel pump and cover assembly.
3. Position the new fuel sender strainer on the modular fuel sender and push on the outer edge of the fuel sender strainer until the fuel sender strainer is fully seated on to the sender assembly.
4. Install the fuel sender assembly into the fuel tank using tool J39765 Fuel Sender Locknut Wrench or an equivalent.
5. Reinstall the fuel tank.
6. Lower the vehicle.
7. Add fuel to the fuel tank.
8. Connect the negative battery cable.
9. Reinstall the fuel tank filler pipe cap.
10. Inspect for fuel leaks.
11. Turn the ignition switch ON for 2 seconds.
12. Turn the ignition switch OFF for 5 seconds.
13. Turn the ignition switch ON .
14. Check for fuel leaks.

91 Sevelle is operated using an electric fuel pump that is located inside of the fuel tank. Either the pump needs to be replaced, or, you have other problems and the computer is telling the fuel pump not to turn on.

I would suggest that you test the voltage going to the pump as well as the pressure on the lines using a fuel pump tester made for a Fuel Injected Vehicle.

If you attempt to spray a small amount of carb cleaner or WD40 into the throttle body and it tries to start when you crank it, you need a new fuel pump. You can spray a small amount of gasoline into the throttle body, reinstall the intake hose & try to start, sometimes the car will run until the fumes are gone. Use caution to prevent fires due to fuel getting onto areas other than inside the iintake/throttle body. Vent until fumes are gone if you accidently spill fuel to prevent possible fire caused by backfiring.

The fuel tank has to be removed to remove the fuel pump assembly, pumps are available as OEM or aftermarket pumps alone, or complete pump assembly. It is easier for those inexperienced to replace the entire assembly.

Good luck.

this is a very common problem. GM has issued a service bulletin to replace the wiring connector at the fuel pump assembly on top of the tank. check the end of the plug for burnt terminals. the service bulletin states that these corroded connectors cause a voltage drop that results in repeated pump failures.