Author Topic: 76 Eldorado fuel injection  (Read 3283 times)

Offline JerRita

  • JerRita #15725
  • Posts: 341
  • Our 1987 Fleetwood Brougham Station Wagon
76 Eldorado fuel injection
« on: August 23, 2015, 08:56:49 PM »
Are there any issues or common problems w/ a 76 Eldo w/ fuel injection vs the carb model? Looking at one but don't want problems Thanks
Jerry and Rita Trapani #15725 Caddymaniacs

Offline 76eldo

  • Posts: 6648
  • CLC Number: 22443
  • Name: Brian Rachlin
Re: 76 Eldorado fuel injection
« Reply #1 on: August 23, 2015, 09:28:45 PM »
Lots, in my opinion.

1.  Injector O rings must be changed if you have no record of that being done.
     They can leak suddenly and start an engine fire.

2.  There a rudimentary ECU that runs the electric fuel pumps and the injectors. 
      Not known to be problematic, but it's electronic and it's old...

3.  Two temp sensors on the intake manifold that go bad.

4.  Fast idle valve that goes bad.

With a few extra HP with the injection, and the exclusivity of the rare option, it's a plus to some, and a minus to others.
Personally, I would rather have a carb.

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Offline bcroe

  • Posts: 3893
76 Eldorado fuel injection
« Reply #2 on: August 23, 2015, 11:31:28 PM »
Quote from: JerRita
     Are there any issues or common problems w/ a 76 Eldo w/ fuel
injection vs the carb model? Looking at one but don't want problems

The ECU on 70s Cads can fail without warning; I recommend carrying a spare.  They are repairable. 

In addition the fuel pump circuit likes to burn out the ECU circuitry.  This can be avoided by
installing a relay circuit so the current bypasses the ECU.  Instructions on my PHOTOBUCKET
first album, or The SelfStarter a few years back.  Bruce Roe
     http://s93.photobucket.com/albums/L71/bcroe/

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

Offline 35-709

  • Posts: 5348
  • The most valuable antique is an old friend.
  • CLC Number: 4719
  • Name: G. Newcombe
Re: 76 Eldorado fuel injection
« Reply #3 on: August 24, 2015, 07:49:09 PM »
Fast idle valves fail often and are hard to find.  Unless I was electronically talented as Bruce Roe is, I wouldn't touch early FI with a 10 foot pole.  But, then again, if you have a problem Bruce is very helpful!
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

bill06447

  • Guest
Re: 76 Eldorado fuel injection
« Reply #4 on: August 24, 2015, 08:43:14 PM »
The ECU is still available as an off-the-shelf AC Delco part but with modernized internal components. O-rings are as prone to failure as any other fuel injected vehicle; the whole set is available at your nearest parts store for under $10 and as with any older vehicle should be changed. Definitely use an external relay for the fuel pumps; you should do the same with your headlights to save your light switch. I'm ditching the carb on my 78 and going with FI from a 76. They don't refer to carburetors as "toilet bowls" for nothing. But then again there is nothing electrical or mechanical I would shy away from...

Bill

Offline bcroe

  • Posts: 3893
76 Eldorado fuel injection
« Reply #5 on: August 24, 2015, 09:13:39 PM »
Quote from: bill06447
The ECU is still available as an off-the-shelf AC Delco part but with modernized internal components.  Bill     

I would like to hear more about replacements, like how you get them and price.  They made a few
dozen versions of the 70s ECUs; are you saying they are all available?  Bruce Roe

Offline 76eldo

  • Posts: 6648
  • CLC Number: 22443
  • Name: Brian Rachlin
Re: 76 Eldorado fuel injection
« Reply #6 on: August 24, 2015, 11:33:39 PM »
The only problem with carburetors is that people expect them to work forever and don't want to spend the money for a pro rebuild when it's called for.

Putting a 76 injection unit on a 78 is going to be nothing but problems and a lot of work for nothing.

Different fuel tank and sender and pump.  Second pump on right side frame rail, and completely different fuel line set up.  Front filter in front of engine, different wiring, probably a different distributor too.

A lot of work for not much gain, possible a few HP if you can get it to run right.

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Offline bcroe

  • Posts: 3893
76 Eldorado fuel injection
« Reply #7 on: August 25, 2015, 12:04:54 AM »
Quote from: 76eldo
Putting a 76 injection unit on a 78 is going to be nothing but problems and a lot of work for nothing.

Different fuel tank and sender and pump.  Second pump on right side frame rail, and completely different fuel line set up.  Front filter in front of engine, different wiring, probably a different distributor too.

A lot of work for not much gain, possible a few HP if you can get it to run right.   Brian   

Is the tank different?  I would just swap the tank pickup/sending unit.  AND I would put a single
high pressure pump in the tank, never mind a rail mounted pump.  The 78 425 engine requires a
different ECU than the 76, and different injectors.  The HEI must be an EFI unit.  The wiring on
those cars is kind of scary at this age; I would overhaul it or make a new harness.  Bruce Roe

Offline 76eldo

  • Posts: 6648
  • CLC Number: 22443
  • Name: Brian Rachlin
Re: 76 Eldorado fuel injection
« Reply #8 on: August 25, 2015, 07:26:05 AM »
If the tank isn't different at least the complete sender section with pump is.

It's just a nightmare of a job with no real gain.  In my opinion.

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Offline mgbeda

  • Posts: 623
Re: 76 Eldorado fuel injection
« Reply #9 on: August 25, 2015, 07:17:03 PM »
The tank is a bit different- on FI cars they welded in a baffle around the bottom where the pickup sits.  I think that was to make it hard for fuel to slosh away from the pickup when the tank was low.

-mB
-Mike Beda
CLC #24610
1976 Sedan DeVille (Bessie)

bill06447

  • Guest
Re: 76 Eldorado fuel injection
« Reply #10 on: August 25, 2015, 07:31:02 PM »
I would like to hear more about replacements, like how you get them and price.  They made a few
dozen versions of the 70s ECUs; are you saying they are all available?  Bruce Roe

bill06447

  • Guest
Re: 76 Eldorado fuel injection
« Reply #11 on: August 25, 2015, 07:44:55 PM »
The only problem with carburetors is that people expect them to work forever and don't want to spend the money for a pro rebuild when it's called for.

Putting a 76 injection unit on a 78 is going to be nothing but problems and a lot of work for nothing.

Different fuel tank and sender and pump.  Second pump on right side frame rail, and completely different fuel line set up.  Front filter in front of engine, different wiring, probably a different distributor too.

A lot of work for not much gain, possible a few HP if you can get it to run right.

Brian

I should have clarified; the whole 76 EFI engine transaxle setup is going in the 78 (the engine and transmission has around 500 miles on it since rebuild-the paint hasn't even burned off the heads yet) The tricky part (for me anyway) will be installing the ECU inside the dash and running the harness. The EFI uses a completely different but separate harness that runs under the right side of the dash to the ECU, with a lead across the car to switched power in the fuse box. Oil pressure, coolant sensor, etc. wiring is common with both engines. The tank and pumps (and pump bracket) I have from the donor car and will be swapped as well. Factory holes are already in the 78 frame for the fuel pump mounting bracket. The donor car even came with a new old stock radiator installed. Fuel line setup is identical to the 76 on the 78. If it ends up trying my patience too much, I have an extra 500 carb intake that will take no time to swap in.

Bill

Offline bcroe

  • Posts: 3893
76 Eldorado fuel injection
« Reply #12 on: August 25, 2015, 08:05:49 PM »
Quote from: bill06447
The ECU is still available as an off-the-shelf AC Delco part but with modernized internal components.

I'm ditching the carb on my 78 and going with FI from a 76. They don't refer to carburetors as "toilet bowls" for nothing. But then again there is nothing electrical or mechanical I would shy away from...Bill   

Building up a 76 EFI, hope it works out.  Get that blue and white 70s EFI book always on Eb+y. 
Any ECU issues, send it here.  I would solder across that set of connectors a couple feet below
the ECU, and also the big purple wire to the starter. 

Thanks for the listing, but just what site did you find it on with prices; I didn't see them. 

The listing seems to say "remanufactured", that means to me repaired with the same old stuff. 
No "modernized internal components"; don't know how that would even apply here. Bruce Roe

Offline Eric DeVirgilis CLC# 8621

  • Posts: 7036
  • Name: Eric DeVirgilis
Re: 76 Eldorado fuel injection
« Reply #13 on: August 25, 2015, 08:24:40 PM »
If the tank isn't different at least the complete sender section with pump is.

It's just a nightmare of a job with no real gain.  In my opinion.

Brian

Amen.

Echoing Brian's comments that this scheme is a terrible idea.

Irrespective of the subjective costs/benefits, such a conversion will absolutely do damage to the value of the car. Many buyers are leery of Factory T Code fuelies as it is, nevermind one that had been converted.

Strongly recommend servicing the carb as needed, when needed - as the Cadillac Gods intended.  8)
A Cadillac Motorcar is a Possession for which there is no Acceptable Substitute

Offline Scot Minesinger

  • Posts: 6004
Re: 76 Eldorado fuel injection
« Reply #14 on: August 25, 2015, 08:33:09 PM »
Yes, I agree that a carb is far less trouble and keeps value of car so that your options are open.  It is not difficult to rebuild a carb, and would suggest doing that instead of changing fuel tank, fuel lines and engine.  You do not want to modify a 78 such that you are the only one that can work on it besides maybe a few on this column-I have made that mistake before.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

 

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