1976 fuel injected cadillac eldorado fuel pump

[clint]

Does anyone know where the fuel pump is on a fuel injected 1976 Cadillac Eldorado? And how would I take it off? 

[76eldo]

Actually there are two.  One in the fuel tank, and one on the passenger side frame rail towards the rear wheel on the inside of the frame.

Brian

[SIPLOWGUY]

Actually there are two.  One in the fuel tank, and one on the passenger side frame rail towards the rear wheel on the inside of the frame.

Brian

I concur. The in tank is low pressure pusher to the high pressure on the frame.

[TJ Hopland]

Also the relay for both pumps is located in the ECU and its common to have issues with the connectors and circuit board.

[Gene Beaird]

And if the fuel pump is noisy, it's usually an indication that the lift pump in the tank has failed.  So if that's the case, replace the lift pump and see how things are. 

As TJ says, the relay for those pumps is in the ECU under the dash.  As the pumps and circuitry age, the power draw through the undersized wires to the ECU can increase, burning circuits on the ECU, causing the ECU to fail.  You can, and should, add an external relay to take the load off the ECU.  Because there are no new ECUs available. 

[bcroe]

Recently I had a tank pickup for my 79 Eldo rebuilt using a high pressure pump.  This should
replace the other pump and other stuff in the frame with just an in line filter.  However, I
haven't gotten the car back on the road for verification tests just yet. 

I suppose someone in the know will say that such a pickup unit is already available off
the shelf.  I would love to hear about that.  See info on adding a fuel pump relay for a 70s
on the first album of my PHOTOBUCKET. 

     http://s93.photobucket.com/albums/l71/bcroe/

(that is a lower case "L"71, not an upper case "i"71)

  click on an Album
  click on a picture to enlarge + description

BRUCE ROE   

[Tspain]

Hello i have a 76 Eldorado.  It all of a sudden wouldnt start. It fuel injected.  It has a relay in the circuit outside the ecu one. I have checked connections and contacts on external relay and cleaned all grounds and re connected them. It also had electronic fan as well the relay is the same as fuel relay. I swapped relays fan and fuel expecting problem to occur in fan but car started fan and fuel pump rumming for about 5 to 8 minutes then shuts off. Swapped them back and nothing.  Waited a couple days.car wouldn't start. Swapped relays again and started and ran 5 to 8 min and shut off. Tried new external relays stiil wont start. Hoping for some guidance.  Thank you!

[bcroe]

Unfortunately those cars did not use a relay in
the EFI, but many have been retro fitted with one
to avoid a failure in the fuel pump supply. 

An engine needs air, fuel, and spark to run. 
Which one are you missing?  The original timing
chain can fail from aging of the plastic and
throw the valve/ignition timing off, check it
for slack. 

The ignition is a standard HEI, test lights can
indicate its operation. 

If dumping a couple spoonfuls of gas into the
throttle body lets it start and run briefly, it
is not getting fuel.  Start looking for fuel
pressure, Noid lights will indicate if the fuel
injectors are operating.  If the ECU has failed,
send it here for test/repair. 
good luck,
Bruce Roe  bcroe@juno.com  CLC # 14630

[79 Eldorado]

You should have the EFI Diagnostic manual if you do not already. See post nr 6 of this thread:
https://forums.cadillaclasalleclub.org/index.php?topic=167249.msg511579#msg511579

The external relay is something which Bruce suggests to avoid a common failure. I installed one of Bruce's external relays on my 1979. Here's a link to my install:
https://forums.cadillaclasalleclub.org/index.php?topic=153100.msg414525#msg414525

To start your car you should turn the key forward to the on position but not immediately to the "start" position. In the "On" position wait for about 3 seconds before cranking. During that 3 seconds you should hear your fuel pumps. If you do not then your line of thinking is reasonable. If you hear the pump running it's not the relay.

Also note that the pumps should only run 2-3 seconds in the "on" position so after that you will not, and should not, hear them unless you cycle the key off/on again or you start the car.

Scott