Author Topic: Electric Fuel injection  (Read 403 times)

Offline 75DevilleFMBlue

  • Posts: 4
  • Name: Dakota Freeman
Electric Fuel injection
« on: June 19, 2017, 08:02:16 AM »
Hi all,

I am new to forum. I recently acquired a new project. A 1975 Deville w/EFI. It is an original EFI car that has been stored since 1989 (with 3/4 of a tank of gas. I got it home. Took it down to just the block and freed up the bottom end and send in the heads for a resurfacing and valve grind. While waiting on heads to return I wanted to drop tank and start replacing/refurbishing fuel tank, sending unit and pump. I dropped the tank to find a series of holes across the front of the tank just above the pinch weld that deem it unusable. I then pulled the sending unit and found a solid 1/8" of varnish and fuel solids caked onto it. Generally I would replace it without question but I can't seem to find parts for this system. I would like any help I can get and don't mean to keep the tank or sending unit original if parts are expensive. If anyone has any ideas about throwing a cheap readily available pump in the tank or possibly has a write up on how to replace it with an available sending unit and pump please let me know. It would be great if someone knew or had a write up that gave info on get X tank use Y sending unit and pump and modify this and that. Also if someone could tell me what years the EFI was used with minimal changes that would be great. I do have the service manual and EFI service manual and that has been helpful I just can't seem to find parts. Thanks in advance for any help anyone can offer.

Dakota Freeman

Offline TJ Hopland

  • Posts: 6589
Re: Electric Fuel injection
« Reply #1 on: June 19, 2017, 08:13:48 AM »
Bruce Roe is our active on the forum EFI expert and I'm sure will be along soon with some details for you.   I know he has been experimenting with an in tank pump solution.   

Have you been able to find any replacement tanks for that car?    Is this going to be an original show car or more of a driver?   I have recently read about a guy that was able to fit a new EFI tank from another car in a 70's cad.   GM had a lot of tanks with the center fill back in that era.   Most of them are a little smaller than the Cad which is good because it gives you some room to work only down side is shorter range.     Tanks Inc is one of the companies that makes EFI tanks for older cars. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline 75DevilleFMBlue

  • Posts: 4
  • Name: Dakota Freeman
Re: Electric Fuel injection
« Reply #2 on: June 19, 2017, 08:23:52 AM »
cost and reliability are a bit more important to me than originality when it comes to the tank and sending unit. I won't be changing any of the interior, body or drivetrain but underneath I'm fine changing in hopes of using parts that are more available, more reliable and better cost. Also thanks for the lead on the tank I haven't yet been able to find an exact match but some I thought looked very similar that I wondered if I could make work. But they are for carb cars. I just can't imagine what the difference a tank would play in carb vs EFI. I always though of a tank as more of just a holding vessel and the pump and sending unit would be EFI specific but according to resources the tank is different if someone could explain how so that would be great.
« Last Edit: June 19, 2017, 08:26:50 AM by 75DevilleFMBlue »

Offline TJ Hopland

  • Posts: 6589
Re: Electric Fuel injection
« Reply #3 on: June 19, 2017, 08:39:06 AM »
Bruce will know for sure what the differences were between the EFI and carb tanks in this era.    When we got into the 80's with the in tank pumps one of the big changes was they added baffles inside the tank to increase the chances of the pump not loosing prime when the level was low.   With a carb you had the mechanical pump which pumped air alright plus float bowl in the carb acted as a reservoir and allowed air to escape so it wasn't a big deal.    Electric pumps don't pump air well if at all and the only way for air that does get in to get out is either through the injector or take the trip through the regulator and all the way back to the tank.

I will see if I can find what forum I read about the guy using the different tank.   I think he had a 70 Deville and used a tanks inc tank from a Cheville.   He was doing an aftermarket EFI system.   He didn't sound like an advanced fabricator that would have been modifying sheet metal and fabricating complex brackets.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #4 on: June 19, 2017, 11:25:02 AM »
Hi, I responded to an email from you.  I have been testing a single pump solution
in my 79 Eldo, I don't believe the actual tank is any different.  Mine is a previous
diesel tank (water retainer removed) to get extra gallons.  My pickup was in bad
shape, and a lot of somewhat subtle repairs were needed to get it functional again. 

Lots of 70s EFI info on the first albums of my PHOTOBUCKET.  Bruce Roe

     http://s93.photobucket.com/albums/L71/bcroe/

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

Offline 75DevilleFMBlue

  • Posts: 4
  • Name: Dakota Freeman
Re: Electric Fuel injection
« Reply #5 on: June 19, 2017, 11:34:27 AM »
So I guess my current thoughts are after seeing your reply Bruce is...carb conversion sounds like a much better option. Is there a good write up on what is involved in converting?

Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #6 on: June 19, 2017, 12:23:10 PM »
So I guess my current thoughts are after seeing your reply Bruce is...carb conversion sounds like a much better option. Is there a good write up on what is involved in converting?   

A lot of owners have gone that way, partly because of unsolvable problems with the
Cad 70s EFIs.  From my own experience, I have tried to solve many of the common
issues.  Conversion to a carb will be more complex than fixing the EFI, you would best
find a parts car for all the pieces that will be needed. Obviously it involves replacing
or reworking the intake manifold with everything on it, the tank, all the fuel plumbing
between them, and a bunch of wiring (mostly removal).  good luck, Bruce Roe

Offline 75DevilleFMBlue

  • Posts: 4
  • Name: Dakota Freeman
Re: Electric Fuel injection
« Reply #7 on: June 19, 2017, 02:38:49 PM »
I would prefer to stay with the EFI for originality but I've heard horror stories of leaks and fires and parts seem to be non existent. My original thought was to throw in any old gm center fill gas tank that will fit and reuse my sending unit after cleaning it and replacing the low pressure pump. I still wonder if I couldn't throw in a generic similar sized tank and reuse my sending unit. What's the chance it is worth reusing /rebuilding after 30 years of sitting in old fuel solids and are there replacements for the in tank fuel pump? I had already planned on replacing all the injector O rings and appreciate the upgrade ideas I just hate to pour so much time into something and always be chasing down the next weakest link if that makes sense. Thanks again for the help.

Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #8 on: June 19, 2017, 06:28:57 PM »
RENU has some pictures of restoration of tanks with big holes.  The couple they did
for me look like they will have a long life, though I regard tanks (and transmissions,
and brakes) as a regular maintenance item, to avoid serious problems on the road. 
That model might need a tank pump even with a carb, check it out.  If so it would
require a control if the EFI and ECU are removed. 

All my cars were available with an extra capacity tank for a diesel engine.  Since
I like to make as few stops as possible for a long trip, I change the pickup and cap
to gasoline using these tanks.  Probably the biggest tank for your car is the original. 

With much of the fuel system at 40psi, you need to take very good care of it.  Some
other reoccurring problems were burning up the pump power circuit, which you can
solved by wiring a common relay into your car.  And dropout of the first true electronic
MAP sensor, no longer available, but I have developed a drop in replacement.  The 2
special temp sensors fail, but some of us have successfully petitioned the original
mfgr to keep making them. 

The above cover a considerable part of of the failures that gave the 70s EFI a
bad reliability reputation.  The last biggie is the analog circuit Engine Control Unit. 
ECUs can fail suddenly, usually its an integrated circuit or a relay.  But just about all
of these failures are simple and cheap enough to repair.  As insurance I recommend
having a spare in the back, swap them every year. 

Bruce Roe
« Last Edit: June 19, 2017, 06:36:02 PM by bcroe »

Offline V63

  • Posts: 233
  • Name: W Link
Re: Electric Fuel injection
« Reply #9 on: June 19, 2017, 06:38:10 PM »
The EFI tank is different in that it has an internal 'well' that prevents the in tank pump from running dry of fuel.

There is an after market 'well'  available at nominal cost, try summit racing.

Having owned a few EFI Cadillacs, there is a noticeable smoothness and assertiveness in performance  Yes, the O rings need service...no big deal. I remain impressed with the system, and certainly never consider reverting to a carburator.  BTW Mercedes used the system 1973-4.

I have a good used std tank for $100, but it is in AZ. I could get it to AR as I plan travel there soon.


Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #10 on: June 19, 2017, 07:07:39 PM »
Quote from: V63
   The EFI tank is different in that it has an internal 'well' that prevents the in tank pump from running dry of fuel. There is an after market 'well'  available at nominal cost, try summit racing.

Having owned a few EFI Cadillacs, there is a noticeable smoothness and assertiveness in performance  Yes, the O rings need service...no big deal. I remain impressed with the system, and certainly never consider reverting to a carburator.  BTW Mercedes used the system 1973-4.

I have a good used std tank for $100, but it is in AZ. I could get it to AR as I plan travel there soon.

Info on special tank features would be welcome; I haven't been inside enough of
the EFI tanks to know. 

The 76 Cosworth Vega EFI was developed first, then the 70s Cad EFI.  There are
so many common features this is obvious (to those who like to snoop electronics). 
But the Cad still was a huge step forward, making a long list of serious improvements
never seen in the Cosworth.  The most significant (to me) was a true electronic MAP
sensor, replacing a clever but extremely clumsy electro mechanical unit.  That MAP
wasn't very reliable, but by 1980 completely solid state MAPs were excellent. 

There were a lot of parts and ideas traded across the ocean.  I haven't seen the
works of Mercedes system, but given the date and fast rate of evolution, I doubt
it was as sophisticated as the Cosworth.  Bruce Roe

Offline V63

  • Posts: 233
  • Name: W Link
Re: Electric Fuel injection
« Reply #11 on: June 19, 2017, 07:59:59 PM »
The Mercedes system, (its a Bosch system really) was fundamentally identical to the Cadillac (also Bosch) EXCEPT MB fired 2 injectors (4 phase) at a time whereby the Cadillac was 4 injectors at a time (2phase). I do not know why they did that? Especially with growing emission sensitivity.

The Cadillac system introduced in 1975 predates the 1976 Crosworth?

The (1967)  VW beetle was the first car with a computer control  and FI (Bosch EFI)
« Last Edit: June 19, 2017, 08:05:54 PM by V63 »

Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #12 on: June 19, 2017, 09:34:13 PM »
The Mercedes system, (its a Bosch system really) was fundamentally identical to the Cadillac (also Bosch) EXCEPT MB fired 2 injectors (4 phase) at a time whereby the Cadillac was 4 injectors at a time (2phase). I do not know why they did that? Especially with growing emission sensitivity.

The Cadillac system introduced in 1975 predates the 1976 Crosworth?

The (1967)  VW beetle was the first car with a computer control  and FI (Bosch EFI)

I don't know how the assembly line dates fall, but the Cad system DESIGN
incorporated a bunch of things the Cosworth didn't.  The new MAP was a huge
advance; Cad also used laser trimmed resistors which were very accurate and
kept that accuracy even today.  The Cosworth ECU was mated and adjusted to
individual engines; the Cad ECU was an interchangeable part.  The injector
driver circuits were identical (unusual high side driver) including a custom
driver IC chip, which hasn't been available on the market.  I suspect that
chip came from Bosch, first for Mercedes.  Same injectors and pumps.  The
Cosworth only used one other type IC, a very short lived early triple operational
amplifier.  The Cad used a quad op amp designed for auto aps, along with a
series of other excellent types originated in silicone valley, that are still in
use today.  All this made practical more complex functions and more accuracy
than anything proceeding. 

The limiting thing on injector firing time seemed to be, to get the gas in behind
the hot intake valve while it was closed, the sooner the better.  That is possible
with half the injectors fired on alternate crank revolutions, per the Cad and
Cosworth.  You can do best emissions though by individual cylinder firing,
sequential injection (requiring port injection).  Eventually systems got back
to this, after throttle body injection for a while.  I did manage to convert
my 79 Eldo to sequential injection with a digital ECU, but it had other bugs
remaining to be solved.  At high rpms injection timing matters less. 

I don't know anything about the VW system, but given the technology available,
it didn't have any integrated circuits or super precision resistors, limiting the
possibilities.  The 1980 digital systems once again blew away the analog
injection capabilities.  Bruce Roe

Offline V63

  • Posts: 233
  • Name: W Link
Re: Electric Fuel injection
« Reply #13 on: June 19, 2017, 09:41:16 PM »
The MB and Cadillac were both premium, technically advanced cars and maybe the Fi system 'budget' was more liberal? The vega...well, not so much? Maybe it was a cheaper (older technology) system (I wonder maybe closer to the VW system? I too, am lacking in the intimate details of the VW system. Just a thought?

Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #14 on: June 19, 2017, 10:08:42 PM »
I can think of multiple reasons why the Cosworth was limited by timing of
technology, and not budget.  I can't say much about Mercedes, with no
drawings or hardware to compare.  I expect like the General, the internal
drawings were never available.  The only reason I have any drawings is
due to some diligent reverse engineering, over a long time.  Bruce Roe

Offline Phil Weber

  • Posts: 19
    • CLC Member
      CLC Member #30787
  • Name: Phil Weber
Re: Electric Fuel injection
« Reply #15 on: June 25, 2017, 05:11:51 AM »
I have a 76 model Deville and use the std carby tank and a sender/pump unit listed for the Eldorado . This unit on Ebay is what I'm using

http://www.ebay.com/itm/Carter-P74012-Electric-In-tank-Fuel-Pump-W-Sender-Fits-1977-78-Eldorado-7-0L-V8-/181987003482?
pid=193376421&hash=item2a5f454c5a:g:oHkAAOSwLN5WkhK0&vxp=mtr.

Use the Oring kit # sk59 listed for the 77 model . You get the copper washers for the fuel rail and the top mounting rubbers for the injectors . 78 cent ea at Rock Auto.
I've been told that the cause of the fires in the early models was the rubber hose from the fuel rail to the regulator . If you have this type swap it for the later bolt on type.

Send your computer to Bruce and have him check it out . Get him to fit one of his modified MAP sensors . Very reasonably priced and fast turn around.

Good Luck

Phil

Offline Driver8

  • Posts: 71
  • 1979 Cadillac Seville
  • Name: Mark Allen
Re: Electric Fuel injection
« Reply #16 on: June 25, 2017, 08:26:26 AM »
Hi, yes I agree on Rock Auto. I have been able to 'stock up' on O-ring kits, injectors and more for pennies on the dollar. I even bought 2 exact NOS OEM designed electronic fuel pumps on close out pricing. (They have several generic style as well, but they will require mods to install properly/safely)

No matter the mileage driven, every 4 years or so, I pull the rail off and replace all the rubber O-rings and seals.  Once you do it the first time, its a piece of cake and goes very quickly.

When RockAuto couldnt get the rail seal kits for a while, I had the idea to go to a local HVAC supply house and obtained bags of the copper O-ring seals for the fuel rail for a couple bucks. I just brought an original with me and they matched it up right off. They work flawlessly. copper or brass would be fine, soft enough to really seal up tight but once unscrewed best to use a new one again because of the indented marks when they get seated and tightened in place.

Change out all/any of the rubber supply/return fuel lines with Gates Barricade EFI hose (multi-layered reinforced hose) and its immune to ethanol breakdown as well. Add in high quality stainless steel fuel hose clamps while your in there. Many of my fuel hoses were ready to just crumble. Soft like room-temp butter, cracks everywhere... all that pressure in there, especially between the electric pump and the regulator... scary stuff for sure.

Bruce Roe was able to evaluate my 2 ECUs, he made needed adjustments, replaced the bad MAP sensors and instructed me with adding in the external relay mod to prevent further issue inside the ECU.

I think its worth the extra effort to do everything possible to keep the '70s EFI running. It IS one of the coolest and most unique things about your car. Do anything possible, IMHO, to avoid a carb conversion.

We are fortunate enough right now to still have parts out there brand new and someone like Bruce Roe to have you safely drive around in 2017 enjoying your '70s EFI Cadillac.

UPDATE:  Here is a DROPBOX link to some random pics from the fuel system work. Including the NOS German made-Carter pump I was able to get from RockAuto couple years back.

picture link>>>>>>>    https://www.dropbox.com/sh/mwme7fxsd01rsqa/AADuecynfSWqOKmaoQCwslbpa?dl=0

GLTY and enjoy the experience under the hood and behind the wheel :)    Mark~
« Last Edit: June 25, 2017, 09:40:09 AM by Driver8 »
Mark Allen  CLC # 28250
'79 Cadillac Seville  http://bit.ly/1VEbnNo
'15 Chrysler 300s   http://tinypic.com/r/2lntu9z/9
'99 Jeep Grand Cherokee Limited   http://bit.ly/1VE758Q

Offline Phil Weber

  • Posts: 19
    • CLC Member
      CLC Member #30787
  • Name: Phil Weber
Re: Electric Fuel injection
« Reply #17 on: June 25, 2017, 03:36:17 PM »
I wish you could still buy those pumps now .
The pumps they sell as a replacement are too long and too small in diameter . They also run too much pressure and the Airtex pump I tried screamed like a banshee .
To fit properly on that bracket you need the outlet to come out the side like that pump you have .

I ended up using a std. Carter pump and relocated it to the chassis directly in front of the fuel tank .

Mark.........What model is your car ?

Phil

Offline Driver8

  • Posts: 71
  • 1979 Cadillac Seville
  • Name: Mark Allen
Re: Electric Fuel injection
« Reply #18 on: June 25, 2017, 04:38:48 PM »
I wish you could still buy those pumps now .
The pumps they sell as a replacement are too long and too small in diameter . They also run too much pressure and the Airtex pump I tried screamed like a banshee .
To fit properly on that bracket you need the outlet to come out the side like that pump you have .

I ended up using a std. Carter pump and relocated it to the chassis directly in front of the fuel tank .

Mark.........What model is your car ?

Phil

Hey Phil,

I know where you're coming from on the pumps, I had ordered a couple before I decided to seek out an exact original, including an Airtex. They did not bolt up properly, and yes they were noisy too. I was lucky to get my hands on that NOS German made exact fit pump, let alone at a discount. As far as build quality goes... the Airtex feels like a Bic pen when you pick it up... where-as the German Carter pump, well... it feels like a bowling ball :)

My car is a 1979 Seville. Wont be back on road till next spring with my work schedule, because I am now taking things apart under the hood to to do some painting, repairs etc and when it all go together again... another new set of EFI seals & O-rings.

Mark~



Mark Allen  CLC # 28250
'79 Cadillac Seville  http://bit.ly/1VEbnNo
'15 Chrysler 300s   http://tinypic.com/r/2lntu9z/9
'99 Jeep Grand Cherokee Limited   http://bit.ly/1VE758Q

Offline bcroe

  • Posts: 1947
    • CLC Member
      CLC Member #14630
Electric Fuel injection
« Reply #19 on: June 25, 2017, 04:44:27 PM »
Anything subject to that 40psi fuel pressure needs excellent maintenance.  Have
been doing tanks here, and the 79 Eldo got converted to a single, in tank high
pressure pump.  This cleans up a few issues: fewer gas and electric connections,
less noise, no running without the knowledge the in tank quit, probably less 12V
drain.  I found the wiring wasn't great; added a weatherproof connector and other
cleanup. 

I contacted K. M. LIFESTYLEs to see if they might be interested in mfr new single
pump pickups, I will NEVER be in that business.  With a couple dozen pics and
even the possibility of borrowing a stock pickup, they acted interested.  I found
3 models to cover the Seville, big cars, and 79 Eldo.  But maybe they would be a
lot more interested, if a list of dozens of immediate customers were presented. 
Better, someone find a later model high pressure tank unit that just drops in. 
There are a lot of subtle points to a submerged assembly like this, I have seen
some done badly. 

More work is happening to my system.  With so much stuff on the left side of
an Eldo engine (trans, speedo cable, ign wiring, steering, etc), I would like to
move the pressure line to the right side, coming forward of the engine and
ENTIRELY AWAY from the exhaust manifold.  Guess turn around the fuel rail
feed point, run a smaller return line across.  Not there yet.  Bruce Roe