: Engine will not turn back on if hot



gornati
04-28-10, 11:13 AM
I have a 78 coupe, with the 425 EFI, it starts everytime easily, engine is good, but if engine gets hot and i turn it on, i have to wait a long time, before i can start it again.

Any advise on this?

Thanks

gornati
04-28-10, 01:53 PM
just adding, starter runs ok, but engine wont start if hot.
And when it starts, starts failing a lot...

deVille33
04-28-10, 09:37 PM
You say it will not start when hot. When you turn the start circuit on does the starter turn the engine over, or does it seem to dead lock? Dead lock - the starter engages, but the engine will not turn over.

deVille33
04-28-10, 09:40 PM
just adding, starter runs ok, but engine wont start if hot.
And when it starts, starts failing a lot...


This suggests that the engine turns over when hot. Does the engine turn over hesitatingly or freely spin? :stirpot:

BRUCE ROE
04-28-10, 10:27 PM
For openers, I would check the 2 EFI temp sensors. Then test the ECU to make sure its delivering the right amount of fuel under all conditions. The MAP sensor in those ECUs often fails. If consequently injector pulse width is reduced, the engine will start on cold enrichment but falter when hot. Swap a spare ECU if you have one. Otherwise, I'll check the ECU for postage. I have a new MAP replacement circuit (no originals available) if its needed. See stuff on Cad 70s EFI on 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 CLC #14630

gornati
04-29-10, 08:41 AM
This suggests that the engine turns over when hot. Does the engine turn over hesitatingly or freely spin? :stirpot:

Hesitates a little but turns over after that.

gornati
04-29-10, 08:45 AM
For openers, I would check the 2 EFI temp sensors. Then test the ECU to make sure its delivering the right amount of fuel under all conditions. The MAP sensor in those ECUs often fails. If consequently injector pulse width is reduced, the engine will start on cold enrichment but falter when hot. Swap a spare ECU if you have one. Otherwise, I'll check the ECU for postage. I have a new MAP replacement circuit (no originals available) if its needed. See stuff on Cad 70s EFI on 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 CLC #14630

Can you tell me where the sensors are located?

How much the new MAP replacement?

gornati
04-29-10, 09:04 AM
For openers, I would check the 2 EFI temp sensors. Then test the ECU to make sure its delivering the right amount of fuel under all conditions. The MAP sensor in those ECUs often fails. If consequently injector pulse width is reduced, the engine will start on cold enrichment but falter when hot. Swap a spare ECU if you have one. Otherwise, I'll check the ECU for postage. I have a new MAP replacement circuit (no originals available) if its needed. See stuff on Cad 70s EFI on 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 CLC #14630

I see you have a lot of experience with those ECU's, i wish i had to know that, before my car were shipped to Brasil...

Anyway, do you do that as a hobbie? or if i send you my ECU by mail are you willing to take a look? if yes PM with a pricing information...

Are you the guy who sells those ECU's on EBAY?

I could definetelly use some or a lot of help with my car, i want and will make run and look like when it came out of the factory.

I have a lot of things to do in the car, including the brakes and some metal work, but so far the most important thing is the engine.

Here you can find some pictures:

http://picasaweb.google.com.br/cams1976/caddy

http://picasaweb.google.com.br/cams1976/caddysp

I already noticed that my ECU was "remanufacturated" so i cant tell exactly without knowing what to test if the ECU is 100%.

What is the black hose on the ECU?

Really appreciate all help from you and DEVILLE33 wich is responding to almost all of my posts.

Regards,


GORNATI

deVille33
04-29-10, 09:25 AM
Very nice appearing car. Some people don't like the '78s as much as the '79s. I find there is something about the '79s that don't appeal to me, although I have several of them. I really like the '78s. I have a '78 deElagance and a '78 Brougham. Both need a lot of TLC.

deVille33
04-29-10, 09:40 AM
Check your battery cables. Not that this will help your hot start problem, but will address your general engine starting. Remove and closely check your ground cable. Swelling along the insulation is an indication of corrosion. The original cables were made of aluminum cable, and over time they oxidize and corrode. Replace if neccessary. Make sure youe cable ends are clean and that your contact surface is clean also.
There is also a ground strap at the starter, make sure it's connections are clean also.
One of my cars has an additional strap to the engine block because of grounding problems.

gornati
04-29-10, 10:28 AM
Very nice appearing car. Some people don't like the '78s as much as the '79s. I find there is something about the '79s that don't appeal to me, although I have several of them. I really like the '78s. I have a '78 deElagance and a '78 Brougham. Both need a lot of TLC.

78 it always had been my dream, had a 81 before...
77 dont have the beautifull, IMO, vertical taillights, and the 79 have way too many holes in the front grille.

this was what i could afford back in end of 2008, it is very expensive to bring those cars to Brasil, i paid originally $1700,00 for this car off ebay.

I want to have some day a H&E Convertible... maybe a 78 or a 80-84.

But first things first, let me put this one on the road first.

I have no idea on where to start, sometimes i want to start disassembling the whole car, and check every inch, but i know this is not the way to go.

How 77-79 devilles you have in total?

gornati
04-29-10, 10:45 AM
what does CLC #14630 stands for?

deVille33
04-29-10, 11:24 AM
I have no idea on where to start, sometimes i want to start disassembling the whole car, and check every inch, but i know this is not the way to go.

How 77-79 devilles you have in total?[/quote]




I know what you mean. I've got a couple cars I'd like to rip to the bones and start back up again. In fact I'm doing that with one of my coupes.

I think I have 15. I had 2 others, but I let them go. Catch and release program. Several are parts cars and some need attention and evaluation. I'm looking at a nice '79 that is for sale at a local dealer, but not sure I want to add anymore cars to my collection at this time. :hmm:

I see someone bypassed the relay circuit board and installed a switch, eliminating the relay. Does the toggle switch regulate both high and low speed circuits?
A lot of people do this because the heat generated at the relay burns out the relay board.

gornati
04-29-10, 11:36 AM
I have no idea on where to start, sometimes i want to start disassembling the whole car, and check every inch, but i know this is not the way to go.

How 77-79 devilles you have in total?




I know what you mean. I've got a couple cars I'd like to rip to the bones and start back up again. In fact I'm doing that with one of my coupes.

I think I have 15. I had 2 others, but I let them go. Catch and release program. Several are parts cars and some need attention and evaluation. I'm looking at a nice '79 that is for sale at a local dealer, but not sure I want to add anymore cars to my collection at this time. :hmm:

I see someone bypassed the relay circuit board and installed a switch, eliminating the relay. Does the toggle switch regulate both high and low speed circuits?
A lot of people do this because the heat generated at the relay burns out the relay board.[/quote]

Eliminate which relay? sorry if it seems a dumb question...

BRUCE ROE
04-29-10, 04:54 PM
GORNATI,

The air temp sensor is in a runner from the carb to
a cylinder. The water temp sensor in the coolant
somewhere; I've seen them at the thermostat or in
the back pipe to the heater. They are interchangeable,
should measure around 1000 ohms at room temp. If
only one is good, make sure it is in the water till you
get another.

I don't charge to check out your ECU. But postage &
customs could be a problem here. Most ECUs need
something; I usually recommend getting them checked
so you can cross it off the problem list. If your
pulse widths are OK, the MAP is probably OK too.
Keeping a spare ECU can help, though people that
far away sometimes just give up the fuel injection and
put on a carb.

I'm retired, advisor to the CLC (Cadillac LaSalle Club). I
think their web site is under construction for a few days.
I don't often sell ECUs, but if I had your model, it
would be a small fraction of the $350 the Ebay guy
wants. Don't know who that is, I wonder if he can
test & repair them as well as I do?

Lots of ECUs are marked "REMANUFACTURED". Not
to worry, they are OK but renumbered. If you give me
your email, I can send a list of ECUs and what they fit.
And my EFI checklist. I'm bcroe@juno.com

The usual problem with mixture, is a failing MAP
sensor in the ECU. If it is putting out low voltage
now, it will soon fail completely. Its on picture 10
(SH 8) of ALBUM-78 K ECU SCHEMATIC. Notice
that there is a test point VMAP where you can measure
the MAP voltage, a 5 pin connector on the side. Or with
ignition on but not running, no hose connected, you
can remove the cover and and measure the MAP voltage
at its pin, or wire jumper 13. It should be 9.5V input,
7 to 7.5V output. The 7V will drop to 0-2V as vacuum
is applied. The hose to the ECU connects to the MAP.
If it is failing, I could install one of my replacements.

Once the engine is hot, your ECU should put out a
fuel injector pulse width around 4ms at idle, 8 ms at
cruise, and near 12ms at Wide Open Throttle.

deVille33 also gives good advice. Most cars that age
should get a new timing chain; the original cam sprocket
has plastic teeth which fall off, block oil flow, and let
pistons hit valves. You can check it without taking the
engine apart.

good luck, Bruce Roe

gornati
04-30-10, 09:28 AM
GORNATI,

The air temp sensor is in a runner from the carb to
a cylinder. The water temp sensor in the coolant
somewhere; I've seen them at the thermostat or in
the back pipe to the heater. They are interchangeable,
should measure around 1000 ohms at room temp. If
only one is good, make sure it is in the water till you
get another.

I don't charge to check out your ECU. But postage &
customs could be a problem here. Most ECUs need
something; I usually recommend getting them checked
so you can cross it off the problem list. If your
pulse widths are OK, the MAP is probably OK too.
Keeping a spare ECU can help, though people that
far away sometimes just give up the fuel injection and
put on a carb.

I'm retired, advisor to the CLC (Cadillac LaSalle Club). I
think their web site is under construction for a few days.
I don't often sell ECUs, but if I had your model, it
would be a small fraction of the $350 the Ebay guy
wants. Don't know who that is, I wonder if he can
test & repair them as well as I do?

Lots of ECUs are marked "REMANUFACTURED". Not
to worry, they are OK but renumbered. If you give me
your email, I can send a list of ECUs and what they fit.
And my EFI checklist. I'm bcroe@juno.com

The usual problem with mixture, is a failing MAP
sensor in the ECU. If it is putting out low voltage
now, it will soon fail completely. Its on picture 10
(SH 8) of ALBUM-78 K ECU SCHEMATIC. Notice
that there is a test point VMAP where you can measure
the MAP voltage, a 5 pin connector on the side. Or with
ignition on but not running, no hose connected, you
can remove the cover and and measure the MAP voltage
at its pin, or wire jumper 13. It should be 9.5V input,
7 to 7.5V output. The 7V will drop to 0-2V as vacuum
is applied. The hose to the ECU connects to the MAP.
If it is failing, I could install one of my replacements.

Once the engine is hot, your ECU should put out a
fuel injector pulse width around 4ms at idle, 8 ms at
cruise, and near 12ms at Wide Open Throttle.

deVille33 also gives good advice. Most cars that age
should get a new timing chain; the original cam sprocket
has plastic teeth which fall off, block oil flow, and let
pistons hit valves. You can check it without taking the
engine apart.

good luck, Bruce Roe

Yesterday i found what looks like a loose sensor, will take a picture and post it here, then i will check them sensors.

My ECU is indeed remanufacturated, but im thinking about getting another one, just in case.

I sent you an email so you can send me that info you offered, i accept it :)

After the eletrical part is ok, i will start checking the timming, belts and cam sprocket.

Im taking notes of everything you guys told me so far, my first daughter is about to born, so i dont think i will have the time to do everything in the next 2 weeks, but i keep you all posted.

Thanks

C. Gornati

deVille33
04-30-10, 11:40 AM
Eliminate which relay? sorry if it seems a dumb question...[/quote]




No dumb question. Above the brake pedal and to the right, there is a board with several relays attached to it. You will find an area in the top left corner which is burned out. Your fan / temperature control relay used to plug in there.

Your fan circuit goes to a series of coils up in your air control box, which sense the temperature of your air box and determine fan speed. The signal goes back to the relay and switches the circuit from high to low, so your temperature control is automatic.

gornati
05-02-10, 04:34 PM
Just a quick update wich may give some information for you guys help me..
Sorry for being a little indivdualist on this one...

Well, my camera has no batteries, while they are charging, i decided to go out and drive around the block with the caddy.

Turn the car on, start at the first turn of the key, idle is extremmly high, i have no tachmeter, but looks like it is between 1500 and 2000 rpm.

Car is cold and when i pump it looses rpm and almost dies, if step on the gas it will shut off (any ideas?)

Left the car running for almost 8 minutes, then idle goes to normal i am able to pump on the gas and the car will not die, did the maneuver to take the car off the garage, i live in an apartment and the biggest car here is a ford ranger, it is very hard to remove the car.

After that iam able drive in the neighbordhood, car runs good, could not get a lot of speed, brakes are not 100%, i would say stopping power is about 15% now...

So the question is, what could be causing the car to have such a high idle and not be able to pump on the gas when the car is cold?

After is hot, idle is normal and runs like a deer...

Will take some pictures of what i think it is a lose sensor and pictures of some wiring i found disconnected.

Again thanks you all

BRUCE ROE
05-02-10, 11:58 PM
Did you check the sensor resistance yet?

Your idle speed is controlled mostly by the COLD IDLE AIR VALVE, shown in the PHOTOBUCKET site. Pushing down on this should slow the engine some. Bruce Roe

gornati
05-03-10, 09:59 AM
Will get the new pics, tonight.

Thanks Bruce.

gornati
05-03-10, 10:47 PM
Well finally had the time to take some pictures...

Here is what i think it is a sensor, if it is a sensor, what sensor is this?

This is located right before the cruise control, diaphragm.

http://img704.imageshack.us/img704/223/sdc12073b.jpg

I dont know, things are slow now here, still need to get the licence plate to take the car to be washed down and have the brakes done.

So, little by little you all help me out.

gornati
05-03-10, 11:02 PM
too big huh?

http://img704.imageshack.us/i/sdc12073b.jpg/

BRUCE ROE
05-04-10, 12:15 AM
You mean, that disconnected cable from the cruise control? Bruce Roe

gornati
05-04-10, 07:56 AM
so, not a sensor at all?

BRUCE ROE
05-05-10, 03:10 PM
Follow it back, does it go to the cruise control unit? Bruce

gornati
05-09-10, 06:01 PM
well bruce, your dang right, the thing i think it was a sensor is the cruise control link.

today i drove the car for a while, brakes are terrible, but after filling up the tank, engine died, but easily turn back on.

I think that could be some old gas and dirt on the lines also.

today i also redone the center panel wich was disasembled.

Next week i might already have the new brake booster and master cilinder, after that with brakes will be much more easy to take the car to shops and fixing all the stuff.

Today is mothers day here in brasil, so i had a very shor time to mess with the car, next saturday will be good, i will wash the car, fix some eletrical problems.

Regards to you all.

Thanks again Bruce and DeVille33

gornati
05-12-10, 09:38 PM
bruce and deville, please check this other topic.

http://www.cadillacforums.com/forums/500-472-425-368/199918-ok-i-finally-received-my-service.html

BRUCE ROE
05-12-10, 11:01 PM
You haven't checked the temp sensors, the MAP sensor, of the cam sprocket yet. Bruce Roe

gornati
05-12-10, 11:48 PM
Well i honestly didnt do my homework, i will re read the topic and check those sensors on saturday.

but i am a little affraid to test the ECU, im afraid to burn the whole thing.

gornati
05-16-10, 07:50 PM
Hey Bruce how much for the MAP replacement circuit?

BRUCE ROE
05-16-10, 10:08 PM
With the distance here, you need to test as many things as possible before sending new parts. Testing an ECU is free, and I could install my replacement MAP for under $100, but round trip shipping could exceed that. Bruce Roe

gornati
05-23-10, 12:17 PM
Hey Bruce, sorry for the delay, my first daughter is about to come this world, so wife is taking a lot of my time!

Well, today i had the chance to test both temperatura sensors, and both @ room temperature, are 980ohms, is this correct?

BRUCE ROE
05-23-10, 04:24 PM
That is a good value for room temp, they look good. Bruce

gornati
05-23-10, 06:03 PM
That is a good value for room temp, they look good. Bruce

Well besides the MAP sensor, is there any other problems in the eletronic/sensors, that could be causing this problem?

Now i think i have to clear the injectors, change their o-rings etc...

There is 2 solenoids, in the vacuum lines, do you have any idea on how to test them?

This problem could be connected to the vacuum lines?

my car is a california car, but some dumb machanic installed the wrong TVS sensor, i already purchased a new one there i will be getting tonight.

With this new TVS i will be able to leave my vaccum lines exactly as it was when came from the factory.

Any new ideas?

BRUCE ROE
05-23-10, 10:35 PM
What is the BENDIX 161 xxxx number on your ECU? Check your MAP voltage.
Note the 5 pin test connector opposite the connector. It has 3 contacts, a gap cut in the board, and 2 more contacts. The very last contact above is the MAP voltage. With ign on, engine not running, it should read 7 or 7.5V ref to ground. Check your timing chain by lining up your timing mark. With distributor cap off, rock the crankshaft by hand, see how far you must go before the dist rotor starts to turn. 6 degrees means the timing set is completely worn out. Bruce

gornati
05-24-10, 09:41 AM
What is the BENDIX 161 xxxx number on your ECU? Check your MAP voltage.
Note the 5 pin test connector opposite the connector. It has 3 contacts, a gap cut in the board, and 2 more contacts. The very last contact above is the MAP voltage. With ign on, engine not running, it should read 7 or 7.5V ref to ground. Check your timing chain by lining up your timing mark. With distributor cap off, rock the crankshaft by hand, see how far you must go before the dist rotor starts to turn. 6 degrees means the timing set is completely worn out. Bruce

o dont have to open the ECU to test it right?

BRUCE ROE
05-24-10, 01:37 PM
On a 78 you don't have to open it, just find the test connector opposite end from main connector. That is if you have the ECU I think, what is the BENDIX 161 xxxx number on your ECU? You could also apply vacuum to the ECU, and see that the voltage drops to a couple volts at high vac. Bruce

gornati
05-24-10, 01:52 PM
i will check the number and voltage.
I know for sure that it is already remanufacturated... with a blue tag.

I will take some pics tonight.

gornati
06-01-10, 08:50 AM
Guys sorry about the lack of updates and info, but my daughter was born on the may 27th, in a few days i will be able to follow thru.

http://farm5.static.flickr.com/4043/4656768494_c45965972d_b.jpg

<a href="http://www.flickr.com/photos/43053041@N08/4656768494/" title="DSC_0796.jpg por Gornati, no Flickr"><img src="http://farm5.static.flickr.com/4043/4656768494_c45965972d_b.jpg" width="680" height="1024" alt="DSC_0796.jpg" /></a>

deVille33
06-06-10, 11:51 AM
Congratuations on your new addition. Have you named her yet?

gornati
06-06-10, 01:07 PM
Congratuations on your new addition. Have you named her yet?


GIOVANNA GORNATI

Italian name, as i am italian...:):):):):highfive::highfive::highfive::h ighfive:

gornati
07-11-10, 01:01 PM
next week i plan to start messing with the engine, will change the spark plugs, cables, oil, oil filter, air filter, TVS valve, clean injectors, change radiator fluids, check transmition oil, differential and last but not least, fix the vacuum lines.

after all this if still there is some problems i will mess with the ECU and etc...

i will keep everybody posted, i am dying to drive this car.

I will also change the brake booster, i received a re-manufactured one from A1 Cardone.

i got also the new trunk seal, and my trunk is full of parts, im just waiting for the air filter and oil filter which i purchased off ebay, the only way to receive it in Brasil.

BRUCE ROE
07-12-10, 01:59 AM
If you remove the injectors, you will need new injector seals. Last original set I checked were completely shot, and a leak will result in a fire. good luck, Bruce Roe

gornati
07-12-10, 09:05 AM
If you remove the injectors, you will need new injector seals. Last original set I checked were completely shot, and a leak will result in a fire. good luck, Bruce Roe

good thing you remebered about that!!! this is in my wishlist in amazon.com, but unfortunately, amazon will not deliver it in Brasil.

I will have to wait to some good soul to put one in ebay and ship it to brasil...

gornati
07-18-10, 05:01 PM
ok bruce, i finally found some time, between the sleeps of my daughter... :)

I was able to run some tests, first, engine cold, ignition OFF, the test point measured a drop of -0.02, with the hose disconnected.

Then ignition ON, engine OFF, hose disconnected, test point showed a value of 1.80, i think my map sensor is bad...

3rd test, turn the car and disconnected the vacuum hose, no differencee at all on the way the engine runs...

Tried to press the fast idle valve and yes, the engine runs in a very low idle, but stalls when i step on the gas.

besides that, everything is the way i told before, starts with a very HIGH IDLE and stalling if i step on the gas pedal...

If i wait until engine is hot, the idle goes back to "normal" and i am able to drive the car without stalling....

if the engine is hot and i turn it off, i am not able to urn it back on...


sorry it took me sooo long to do the tests.




For openers, I would check the 2 EFI temp sensors. Then test the ECU to make sure its delivering the right amount of fuel under all conditions. The MAP sensor in those ECUs often fails. If consequently injector pulse width is reduced, the engine will start on cold enrichment but falter when hot. Swap a spare ECU if you have one. Otherwise, I'll check the ECU for postage. I have a new MAP replacement circuit (no originals available) if its needed. See stuff on Cad 70s EFI on 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 CLC #14630

BRUCE ROE
07-18-10, 09:32 PM
The MAP test point should read at least 7V with the engine not started. Getting that replacement ECU might solve the problem. Then you can get the first one fixed as backup. Bruce Roe

gornati
07-18-10, 09:37 PM
do you have a replacemente ECU?

can you sell me one of the MAP replacements?

gornati
07-18-10, 09:43 PM
by the way, your inbox is full..

gornati
07-19-10, 07:48 PM
well Bruce, the point is i rather go spending $50, with you than 500 in a new remanufactured ECU from NAPA online.

Please if you can, please sell me one with a little bit of instructions i can make it work.

Thanks

BRUCE ROE
07-20-10, 12:53 AM
You ought to try bcroe@juno.com . I might finally have figured out how that Cad in box works. I could send a MAP sensor, but its a worry that it won't get installed properly, or here could be additional problems. I like to completely check the ECU on my tester. How come you changed your mind about the NAPA ECU? Bruce

gornati
07-20-10, 07:14 AM
I rather send you my ecu and you do the job, I will email you today!

I think napa is charging way too much for those, let's not forget that they also charge a extra $84 for core.

And I can't purchase online, I would have to wait until november and go personaly to a store.

gornati
08-06-10, 10:54 PM
Ok, problem FIXED...

Turns out that, no problem in the vacuum lines, no problem in the timing chain or sprokes...

Bruce Roe was dang right!

Problem was only the ECU, i sent him the module, 10 days later i receive it back, just plug it and voila!!! Everything worked as is supposed to work.

Bruce Thanks very much!!! was the best spent money ever!

This guy is good!!!

cheers bruce!