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1977 Cadillac Seville Help!

Started by 1977Seville, October 04, 2009, 02:15:54 AM

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1977Seville

Ok, I bought it for $700 bucks from a 90 year old guy, it looks great, and I love it, it was sitting for 8 months, and it is turning but not turning over, I got a new battery and primed the air intake and it made no difference. How can I get it up and running? The old guy said there was some fuel intake sensor that was bad, but, I dont know. Anyway, it has a newere radiator, fluid, tires, etc. all the power stuff works and it looks good. Help!
Wes'
1921 Chevrolet '490'- in the family since 1972
1941 Dodge Business Coupe- in the family since 1955
1948 Lincoln Continental- in the family from '75-'91 bought back in 2007!
1966 Ford Mustang - (2001)
1977 Cadillac Seville (2018)
1989 Buick Electra Park Avenue (2012;2017;2018)
1989 Buick Reatta (2013)
2004 Lincoln Town Car (2014)
2015 Chevrolet Volt (2017)
Wesley Willison

bcroe

Its still air/fuel/spark with EFI, try to determine which. 
I'd check temperature sensors first, below.

76-79 Cadillac Fuel Injection Repair

Here is some general stuff.  If you think only half
the injectors are firing, check that the black wires
on the injectors have a good ground connection
on the engine.  There are usually 2 bolts grounding
the lugs, one for each bank.
_____________________

There is always the possibility of bad fuel
injectors; it is usually possible to get them cleaned.
Replacing ALL the injector gaskets and high pressure
fuel hoses might save you a fire; be sure to check for
leaks after repairs.
_____________________

Regarding the 76-79 350 and 76 500 engines, they
use different distributors, different fuel injectors, in
fact about the only parts on the engine that are the
same are the temperature sensors.  The computers
are calibrated/adjusted differently.  The 77-79 425
parts are very similar to the 500, but use the same
injectors as the 350.  The throttle position switch
seems to be the same for all models.  The 78 and
later 350 engines use a small bore throttle body on
an aluminum intake manifold, others use a large
bore on an iron intake manifold.  The aluminum
intake has corrosion problems around the coolant
passages and should be checked to avoid leaks.  I
would recommend milling about .030" off and putting
in some of those Mondello fiber gaskets over the
regular valley pan.
_______________________

If you switched computers from one car to another,
a car should at least start and run a bit.  So you can
test a computer in any running car.   Also the SPEED
SENSOR in the distributor is the same.  If you are
taking parts, save the computer.  The computer
parts can be used to fix other computers, and I can
convert a 350 computer to run a 500

You need to know if your car won't run because of
fuel or spark.  Make sure there is plenty of spark at
the plugs. 

Try turning on the ignition but not starting the engine.
You should hear the fuel pump run for about 8 seconds
and then shut off.  There should be 39 psi (3.6 Bar) of
fuel pressure at the injectors.  If no pressure, check
pump power from computer.  There is a fuel pump
fuse in the wiring connecting to the computer.

If pressure is very low, try squeezing closed the hose
on the return pipe from the fuel pressure regulator.  If
this raises pressure its the regulator; if not its the
pumps.  There are 2 pumps, a low pressure pump
in the tank and a high pressure pump mounted in the
frame. 
_______________________

Try this test on the computer.  Take off the air cleaner. 
Turn on the ignition but don't start the engine.  Slowly
pull the throttle all the way open, and you should hear
the injectors click 21 times.  If this works a lot of your
injection system is working.  The electrical unit on the
the throttle body shaft is a multi contact switch which
generates acceleration enrichment pulses plus
detects full open or closed throttle.  It is very reliable,
but sometimes must be adjusted (turned) to close
the closed throttle contact.  Throttle body shaft
bearings can be worn like a carb, and repaired the
same way.
_______________________

The MAP sensor is located in the ECU, fed by a vacuum
hose in the wiring harness.  If there is a leak anywhere,
the engine will run rich.  A short hose inside the ECU
can leak or come off.  Use a hand vacuum tester and
apply a vacuum where the hose attaches to the throttle
body.  Find and repair any leaks.
_______________________

The 78-79 distributor uses an Electronic Spark Selector
module (ESS) mounted in the engine compartment and
connected to a special module in the HEI distributor.  It
provides spark advance (high vacuum) or retard (for
starting) but is essentially independant of the EFI.

The 76-77 distributor is essentially standard except
for a modified curve and the added Speed Sensors.
________________________

Do your periodic maintainance.  Worn out distributor
bearings or weight pivots, bad ign wires, or bad vacuum
advance will severly affect operation.  All of these cars
are so old the timing chain and sprockets should be
replaced regardless of mileage.  The plastic teeth will
be falling off the cam sprocket if not already worn away.
________________________

The SPEED SENSOR is a pair of reed switches operated
by magnets, located in the lower part of the distributor.
There is a 3 wire connector to it.  If it is working, the
switches will alternate closing for a short time, one
switch each engine revolution.  With a meter on the
wires, the white wire will have about 9 volts.  The red
and the black wires  will each briefly rise to about 7 volts
in 2 engine revolutions (one distributor revolution).  If
this fails, the engine may start and barely run by pumping
the pedal hard.

If only one of the SPEED SENSOR contacts is not closing,
none of the injectors (either bank) will operate.  If only one
contact is shorted, one of the injector banks will operate.
If the SPEED SENSOR is unpluged, an ohm meter may
be used to check the contacts.  As the distributor rotates
slowly, there should be a brief contact closing (zero ohms)
alternating between the following pairs of wires
   white to red
   white to black
_______________________

The EGR passages on these systems often get plugged
up.  This will cause the engine to run lean.  I recommend
taking off the EGR valve and throttle body, and cleaning
them out.  If the extra diaphram unit fails, I set them up
with the simpler system used on a 79 Olds 350/403 EGR.
_______________________

The idle air valve is in the throttle body.  The assembly
may be removed by removing the electrical plug and
air cleaner stud, and turning the plastic block 1/4 turn.

The idle speed may fail to shut all the way down if the
idle air valve does not close all the way.  Usually this
can be fixed by use of an extra spacer (like a dime) of
some .040" to .080" thick in the center of the moving
part of the valve.  Power is supplied from the fuel pump
circuit, which will shut down after 10 seconds if the
engine is not running.  If power does not flow through
the circuit, idle speed will be very high.
________________________

The 2 thermistors measure air and coolant temp, and
are interchangable.  These should measure ballpark
1000 ohms if good; usually the failure mode is open
circuit.  An open will cause the engine to go to the hot
mixture level, no cold enrichment.  The coolant sensor
has much more effect on opperation.  So if you only
have one good one, put it in the coolant position to
get things running.
_______________________

If you have a computer you know is bad, I probably can
fix it for you.  Or use parts from it to repair a spare I have. 
You could send it to

Bruce Roe   CLC # 14630
5719 East Skinner,
Stillman Valley, IL    61084-9215
USA

815 234-8039    talk to my answering machine and I'll
pick up or call back
   


35-709

Wow!  Very informative post, Bruce.  Just confirms to me that I'm sticking with carburetors and pre-computer age cars!!
:)  Geoff N.
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 - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

1977Seville

Can I replace the fuel injection with a carb.?
Wes'
1921 Chevrolet '490'- in the family since 1972
1941 Dodge Business Coupe- in the family since 1955
1948 Lincoln Continental- in the family from '75-'91 bought back in 2007!
1966 Ford Mustang - (2001)
1977 Cadillac Seville (2018)
1989 Buick Electra Park Avenue (2012;2017;2018)
1989 Buick Reatta (2013)
2004 Lincoln Town Car (2014)
2015 Chevrolet Volt (2017)
Wesley Willison

bcroe

Sure, lots of cars of that era had 350 Olds with a carb.  Maybe get a parts car,  pull all the EFI wiring, change the intake manifold + carb, add a mechanical fuel pump, after removing the electric fuel pumps rework 3 fuel lines back to the tank and change to a carb tank unit.  Use a carb type EGR control system.  The present HEI should work, or change to one intended for a carb.  78-79 would best change the HEI to get rid of the ESS system.  Install an electric kickdown switch.  Probably need to do something about the air cleaner. 

It would probably be easier to get the EFI running, though.  Your timing chain is probably way overdue for replacement either way, could be the problem.  Bruce Roe CLC # 14630

Tom Magdaleno

Beautiful car, thats one of the few late 70's cars that I would consider a classic.  If you can get the injection working you might get more looks at car shows.  Its interesting to preserve that kind of stuff.  But I wouldn't blame you if you tossed it either.
Tom
'38 Cadillac V16
'71 Buick Riviera
'65 Chevy Truck
'56 Packard Super Clipper

1977Seville

Well, I am going to take it to a friend tomorrow, it may be something simple, I got it for $700! It has new tires, radiator, fluids, etc. And it has the orig. paint and the interior is in pretty good shape, the vinyl top is perfect and it is the orig. And it has a sunroof! The chrome is perfect, paint is in 7/10 condition, but, looks much better after a wax! It was driving as of 6 months ago, the 90 year old I bought it from, said it may be some kind of a sensor, like the coolant sensor, his mechanic told him to replace it and did not, but, I have never discovered a bad sensor that did not allow a car to start, maybe this prehistoric dinosaur of tech. does that? I love it though! It is a great car! My grandpa had a brown 1977 seville
Wes'
1921 Chevrolet '490'- in the family since 1972
1941 Dodge Business Coupe- in the family since 1955
1948 Lincoln Continental- in the family from '75-'91 bought back in 2007!
1966 Ford Mustang - (2001)
1977 Cadillac Seville (2018)
1989 Buick Electra Park Avenue (2012;2017;2018)
1989 Buick Reatta (2013)
2004 Lincoln Town Car (2014)
2015 Chevrolet Volt (2017)
Wesley Willison

Tod - NTCLC

I strongly recommend that you buy a sensor - that is the most common failure with this system.  The sensors are available new from MTD, and you should change the coolant sensor first as that is the one that will have the most impact on starting the car - and yes, these cars can be virtually impossible to start if these sensors are not functioning.

As a workaround, if you have an Ohm meter, check the resistance on the two sensors (coolant temp sensor is located on top of intake manifold, drivers side all the way at the front of engine; air temp sensor is on top of manifold, passenger side, towards the rear).  The sensors are identical and interchangable.  If you check the resistance, on a cold engine you should get around 950 to 1025 Ohms - that would be a working sensor.  If you find that you are not getting that on the coolant temp sensor, but the air temp sensor checks out good, then switch them out - the coolant temp sensor has the most impact, and you may be able to get it started by just making that switch.

If everything else is good (fuel pump cycles, you have spark, etc.), then the sensor is the first thing check. 

Let us know what you find -

1977Seville

Wes'
1921 Chevrolet '490'- in the family since 1972
1941 Dodge Business Coupe- in the family since 1955
1948 Lincoln Continental- in the family from '75-'91 bought back in 2007!
1966 Ford Mustang - (2001)
1977 Cadillac Seville (2018)
1989 Buick Electra Park Avenue (2012;2017;2018)
1989 Buick Reatta (2013)
2004 Lincoln Town Car (2014)
2015 Chevrolet Volt (2017)
Wesley Willison

bcroe

Get an ohm meter and measure the resistance of your 2 sensors.  Let us know.  Then plan to buy 1 more than are bad, for a spare.  One source is Maximum Torque Specialties. 

If you get it running check out the timing chain (can be done without taking engine apart).  If it hasn't failed & been replaced yet, it will soon. 

Bruce Roe CLC # 14630

Otto Skorzeny

Click on the link below my name to find the contact info for MTS and other Cadillac parts and service vendors.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

1977Seville

Ok, we got her running, it runs a little rough and the alternator is no good, but,she is running, updates to follow!
Wes'
1921 Chevrolet '490'- in the family since 1972
1941 Dodge Business Coupe- in the family since 1955
1948 Lincoln Continental- in the family from '75-'91 bought back in 2007!
1966 Ford Mustang - (2001)
1977 Cadillac Seville (2018)
1989 Buick Electra Park Avenue (2012;2017;2018)
1989 Buick Reatta (2013)
2004 Lincoln Town Car (2014)
2015 Chevrolet Volt (2017)
Wesley Willison