New 79 Biarritz owner here with some EFI questions

[seok]

New to the forum, and just picked up a white/white 79 Eldorado Biarritz EFI. Interior/Exterior is in great shape but it is a project. It sat for a yr after the owner passed. it was parked after the brake MC shot fluid all over and lost brakes (fine with me)
but Now it wont fire up. It cranks but wont start. Im not familiar with this early EFI so the only thing i checked so far was the pressure at the release valve near the regulator. NONE.
i drizzled some fuel down the TB and it ran for 2sec so i know its not getting fuel.
What i am asking is what are the proper steps to troubleshooting this system?? ive been reading and searching and learned that is has 2pumps, sensors and a ECU underdash that houses the MAP sensor ran off vacuum. shoud I just use a test light on the underbody fuel pump first? or is there a specific relay/fuse to check first? It ran fine prior to it being parked on the grass after the brake fluid shot out everywhere. so im hoping it is just a fuse/relay. please guide me in the right direction. I wont have access to the car until this weekend so I have plenty of time to research and read all your HELPFULL REPLIES!

[seok]

one more thing, I also noticed that mounted to the TB there is a spring loaded solenoid thing (looks like it controls idle maybe? for cold starts?) anyways, one of the wires on the connector is bare, the insulation has deteriorated and exposed the wire. is this replaceable or do i have to splice and repair?
thanks.

btw, im located in Portland, Or

[The Tassie Devil(le)]

G'day seok,

Welcome to the Forum, and congratulations on your purchase.

The next thing that you should really purchase is a Workshop Manual, as these books are an invaluable tool that will save you a lot of time, and also provide some good reading on those cold Oregon winter nights by the fire.

Bruce.

PS.   You have mail.

[seok]

Thanks Bruce, I will definitely look into one!
My hopes are to at least get it fired up and go from there taking care of any issues after that. it wont be a daily driver until i get it safe and reliable and sell my 95 LT1Caprice
so I have some time. just hoping to get some seasoned, early EFI guys in here to reply 

in response to the mail...no damage! luckily it stayed away from the paint! 

[bcroe]

As recommended get all the relative manuals on 76-79 EFI, I see them on Eba*y all the time.  You should see 40 psi at the injector rail as soon as the key is on.  There is a fuse in the fuel pump circuit, which hen feeds through the ECU to the pumps and the cold idle air valve.  That valve heater on the throttle body valve is on the same circuit as the fuel pumps, though different ECU pin.  You can see a drawing of the fuel pump circuit, the ECU schematic, and a few other things on my PHOTOBUCKET site.  

More info later if you need it, call

Bruce Roe 79 Eldo with injected 403 & switch pitch trans


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

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

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

815 234-8039

[bcroe]

Get the 76-79 EFI manual seen on ebay  160505349186  or  380247886584  or  120375607476   Cadillac Electronic Fuel Injection Diagnosis.  Also try to find a 79 chassis service manual, though the EFI is almost identical to the 76-79 Seville.  A book unique to the car is 1979 ELDORADO BY CADILLAC : ELECTRICAL TROUBLESHOOTING MANUAL . 

This first electronic fuel injection system here suffers from being first.  Reliability has been poor.  However, the 2 most common issues can be avoided with modification, the fuel pump circuit and the MAP sensor.  Bruce Roe

[Dave Shepherd]

AS you will see in the trouble tree and shop manual there are 2 pumps, one in the lt rr frame rail and one in the tank.

[seok]

Bruce Roe, Thanks for the info!
you did bring up another question I was going to ask... modifications? what mods do you know can be done to the relay circuit and MAP sensor (or anything else) to help avoid future trouble?
also would it benefit me to get a carb/intake swap? i dont mind doing any repairs/mods to keep the EFI reliable and factory, also dont mind doing a swap if it will help. as long as I am heading in the right direction. without spending hundreds on parts! of course these invaluable replies help that out 

and thanks to an email from a member i am about to purchase a 79 service manual!
Im loving this forum already and hope I can some day return the favors to others in need here

thanks guys

[bcroe]

seok,

You can see the fuel pump circuit on the 9th and 10th pictures of the first PHOTOBUCKET album, 70s FUEL INJECTION.  The suggested relay won't save a bad fuel pump, but it prevents that from destroying the ECU like so many I have seen.  This and some other stuff are in the Nov/Dec 2010 Cad LaSalle magazine, THE SELF-STARTER.  The MAP replacement is also described on PHOTOBUCKET, this is new but I hope will be far more reliable than the original.  Temperature sensors fail often, but are available.  Check that aluminum manifold, it may be trying to corrode and leak.  Any car that old must have the original timing chain set (with plastic sprocket) replaced with an all steel set.  Beyond that, I recommend carrying a spare ECU backup. 

Some people don't want to mess with the EFI, and convert to a carb.  Any 350/403 Olds setup should work, a Toro or Riv is best with the correct transmission TV cable to the carb.  Bruce Roe

[seok]

That is some great info Bruce. I am NO electrician by any means, the most I have done is wire in a dual electric fan setup and install a stereo on my caprice 
BUT, i THINK i am beginning to understand what your diagrams mean. It sounds like (please correct me, im sure im wrong in many areas) pin C gets overworked, heated and fail from the fuel pumps draw. and by bypassing this pin and running the pumps through and EXTERNAL relay it prevents the possibility of this ever happening? now what about the internal relay? is it still used since the new relay/pumps are tied into pin J now with the Fast Idle air valve?
so... if MY internal fuel pump relay is still good, then this conversion will help prevent a future ECU catastrophe from a failed pump and Pin C right? and IF my relay is BAD at this point/or pin burned, am I looking for a replacement ECU or repair?

My apologies for the ignorance but I have alot of learning to do and im trying to understand. its all new to me but I am a determined guy and wont quit until i understand and accomplish the tasks. unless I pull the few hairs left out of my head and go carbed, which I will still have questions about distributor, fuel lines, and pumps  haha

[bcroe]

Soek,

That is correct, keep the main current out of the ECU.  That current causes contact, board trace, and internal relay contact failures on so many ECUs.  Modified, the current can only affect the (much bigger) external relay, which could easily be replaced if it ever failed.  You will still need the internal relay to drive the external relay and the Fast Idle air valve.  If there is no power to either output now, the ECU may have already failed.  If pin C has burned out but pin J is still receiving power (for a few seconds after the key is turned on), the fix will get you going again.  Bruce Roe

[TMoore - NTCLC]

Seok -

Listen to Bruce - he is the expert on these systems, and has enabled me to keep four of these cars in regular service.

Just a couple of things for you to check before you get to the ECU troubleshooting.  The electric feed to the fuel pumps will have an in-line fuse just a few inches away from the ECU - check the condition of that fuse.

Next would be to check the condition of the electric fuel pumps - one in the fuel tank, and then one on the chassis rail just over the driver's side rear wheel - supply power to these and test to see if they are functional and can deliver the 40p.s.i. to the fuel regulator.

Keep us up to date on your progress.  Although the E.F.I. can be a challenge, a properly functioning system will provide an incredibly smooth running engine, and generally good reliability.

T. Moore

[seok]

Thanks Tod,

Believe me, Bruce has my undivided attention! The responces im getting here are unbelievable.
I have no doubt we will get this thing running the way it should.

I will check the inline fuse and power from the pumps. Ill keep you updated

Matt dennison

[Dave Shepherd]

If it turns out the ecu is bad, a friend and ex co -worker when I was in the field for Cadillac back in the 80's, has a new ecu. I can put you in contact with him.

[76eldo]

Bruce,

Would my 1980 Eldorado benefit from your method of powering the fuel pumps?

Brian

[bcroe]

In 1980 most Cads with the 368 went to an entirely different digital EFI system.  They learned from experience and moved the fuel pump relay outside the ECU I believe.  So they should be fine, though a few 80 Eldos in CA still had the 350 Olds system.  Bruce

[Dave Shepherd]

Correct the 80-81 tbi fi had a seperate fp relay and of course the tbi was completely different thatn the 75-79 system, one 10-15 psi tank pump was used.

[seok]

Updating to keep it alive...

I finally had a break in the weather and did some testing,
luckily the owner had a great condition 79 Service Manual for the car!
With TONS of reading and some great help here from you forum members I feel im on the right path, and learning a lot.
I checked power TO and FROM the ECU on all pins necessary, along with power at the fast idle valve, and the frame rail fuel pump.
It looks like the ECU is fine. and power is making its way to the pump, but the pump is not working.
I havent had the time to check power at the intank fuel pump connector yet.

some things I did find that need attention are, the fast idle valve wire is exposed so I need to rewire that guy. also one of my injector
plugs are broke, so brittle it just crumbled. Are these universal? can I just splice and replace with a donor? and I need the electric plug on top of the
washer fluid bottle, it looks melted. if anyone has info on where to get any of these or has some for sale please let me know.

updates to follow...

[Lasallebob]

I also have one of these beasts, and getting parts and info is tough. I have found a manual from Cadillac that describes the EFI system and its components that came from one of their training classes. Has a diagnostic section and each sensor in the EFI is described. Send me your Email and I'll send it to you, its about 17 pages long. If I get my problems solved I'll let you know what I found and did.
Bob Kazawic     bob.kaz@comcast.net

[Lasallebob]

Since we are talking about EFI problems on a 79 Biarittz, I thought i would jump in here with my problems and perhaps we all can learn something about these beasts!
I did talk with Bruce and received some tips, here is the problem I continue to have, any input is appreciated;
Car will start and run, I can tell the fast idle sensor works because the idle drops off after a minute or so, but the idle seems rough.When i put it in gear and accerate there is a slight hesitation and backfire but then takesoff. Under 40mph at about 20 or 30 mph when I take my foot off the pedal then step on it the car hesitates and backfires slightly and then accerates. Above 40mph it runs fine and performs well, the hesitation and backfire only occurs under 40.

I have done the following :New Plugs, New wires, New distributor cap and rotor, New gas filter, Air filter, Flush of injector sysem and throttle body

Checked the  following,
TPS -21 clicks and correct gap on idle screw, checked vacuum line on MAP sensor,held vacuum OK, Air and Temp sensors read 900 ohms, cleaned fast idle sensor
I have reached the end of my diagnostic capabilites !!  HELP!
Bob Kazawic