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Eric, Automotive Repair Shop Manager
Category: Cadillac
Satisfied Customers: 29384
Experience:  20+ yrs. experience as repair shop manager and technician.
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1978 cadillac seville: fuel injection..v..the fuel pumps located

Customer Question

I have a 1978 cadillac seville fuel injection v-8 fuel not dieasl , where are the fuel pumps located and also do i need both
Submitted: 5 years ago.
Category: Cadillac
Expert:  Eric replied 5 years ago.

ok, you have one in the fuel tank, and one along the left inner frame rail, forward of the rear tire. I always suggest replacing both at same time. Below are directions for both:


Chassis-Mounted Fuel Pump (EFI System)

CAUTION Fuel is under high pressure; if the steps below are not followed, the fuel could spray out and result in a fire hazard and possible injury.
  1. Disconnect the negative battery terminal.
  2. Locate the pressure fitting in the fuel line at fuel rail and remove the protective cap.
  3. Loosely install a special valve depressor (G.M. tool no. J-5420) on the fitting.
  4. Wrap a towel around the fitting to block any spray and slowly tighten the tool until the pressure has been relieved.
  5. Remove the tool and reinstall the protective cap.
  6. Remove the fuel hoses from the pump.
  7. Peel back the rubber boot and remove the two nuts, one from each electrical terminal. Remove the electrical leads.

These nuts have metric threads.

  1. Remove the two screws and flat washers holding the fuel pump to the bracket and remove the pump assembly.

To install:
  1. Install the fuel pump in the reverse order of removal.
  2. Connect the green wire to the positive terminal on the pump and the black wire to the negative terminal. Check to make sure the fuel pump is resting evenly on its two mounts and not grounding against the bracket or frame.

In-Tank Fuel Pump

See Figure 1

  1. Disconnect the negative battery terminal, open the fuel tank filler door and disconnect the sending unit feed wire. Release the fuel pressure.
  2. Siphon the fuel from the fuel tank. If the rear of the car is raised one foot higher than the front, more fuel can be taken out.
  3. Raise the rear of the car and remove the screw securing the ground wire to the cross member.
  4. Disconnect the fuel line, evaporative emission lines and the fuel return lines at the front of the tank.
  5. Support the tank with a jack and wooden block and remove one screw on each side securing the fuel tank support straps to the body at the front of the tank.
  6. Lower the jack and tank enough so that the fuel pump electrical lead can be disconnected. Disconnect the wire.
  7. Remove the fuel tank from the car.
  8. Remove the locknuts securing the fuel gauge tank unit and fuel pump feed wires to the tank unit.
  9. Turn the cam locking ring counterclockwise with a soft non-ferrous punch and hammer. When the lock ring is disengaged, remove it and lift the gauge/pump unit from the tank.
  10. Install in the reverse order of removal. Tighten the fuel tank retaining strap screws to 25 ft. lbs. (34 Nm).

Click image to see an enlarged view

Fig. Fig. 1: In-tank fuel pump

  1. Secure two sections of 3 / 8 in. x 10 in. (steel tubing), with a double-flare on one end of each section.
  2. Install a flare nut on each section of tubing, then connect each of the sections into the flare nut-to-flare nut adapters, which are included in the Gauge Adapter tool No. J-29658-82.
  3. Attach the pipe and the adapter assemblies to the Gage tool No. J-29658.
  4. Raise and support the vehicle on jackstands.
  5. Remove the air cleaner and plug the THERMAC vacuum port on the TBI.
  6. Disconnect the fuel feed hose between the fuel tank and the filter, then secure the other ends of the 3 / 8 in. tubing into the fuel hoses with hose clamps.
  7. Start the engine, check for leaks and observe the fuel pressure, it should be 9-13 psi.
  8. Depressurize the fuel system, remove the testing tool, remove the plug from the THERMAC vacuum port, reconnect the fuel line, start the engine and check for fuel leaks.
Expert:  Eric replied 5 years ago.

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