: How to adjust Carburetor ?

10-19-04, 05:09 PM
I have a Cadillac Fleetwood -79, which had no idle run when the engine was hot. I asked a workshop to fix that, which they did, but now there is another problem.

I cannot start it!
Well, it actually starts when I let the starter run for 20-40 seconds. It started like a charm before they screwed it up.

I would like to have it start at once again, just as it did before. The guy at the workshop told me that it has an "electric carburator"... I dont know what that means. They don't seem to know that engine very well. I've already payed them over $2.000 for fixing this thing.. :mad:

So, If anyone could give me a clue of what might be wrong, what can be checked, or if there is any trick, please reply!

Regards, Andreas

barge master
10-19-04, 07:39 PM
Is the problem just when it's cold? It might be the choke. The choke is electric, that might be what your mechanic was talking about. :welcome:

10-19-04, 07:48 PM
Is the problem just when it's cold? It might be the choke. The choke is electric, that might be what your mechanic was talking about. :welcome:

Yep, only when its 100% cold.

How can I test if the choke is working or not?

More info... The workshop switched sparkplugs to the "right ones". A friend told me that I might need warmer ones, so I just went out to take a look.

I found out that there now is oil around the big gasket, located between the motor block and carburator. That gasket was replaced at the workhouse (its named "gasket set manfold" on my bill). I dont know if they died it in oil upon installation, or if it is leaking all over it. Will ask them tomorrow...

Night Wolf
10-19-04, 09:59 PM
There is a wire connector on the right side of the carb, that is the power for the electric choke...

if is it off, the choke will not close... and make it very hard to start...

.. I do not have a pic, and hard to descrie it.. small connector, IIRC it is grey it slides on and off...

10-19-04, 10:17 PM
if is it off, the choke will not close... and make it very hard to start...

Sure about that? I thought if that wire is disconnected the choke would be on all the time... It might not hurt to try richening the idle a hair, turn both idle screws out a half-turn and see if there is any improvement. If not, return them back to thier original setting. Before you start the car in the morning, take the air cleaner off, and pump the gas. the choke should snap shut.

10-19-04, 10:19 PM

I will check that one tomorrow and see that it has power.

10-20-04, 10:39 AM
There is a wire connector on the right side of the carb, that is the power for the electric choke...

if is it off, the choke will not close... and make it very hard to start...

.. I do not have a pic, and hard to descrie it.. small connector, IIRC it is grey it slides on and off...

Hello Night Wolf!
I am not sure which cable you mean. Here's some photos and a simple sketch of them.

If it's cable #1, then something is wrong. The engine does not start better with that cable unplugged. And when it is hot, it does not seem to care about it.
I have measured it with hot engine. It shows +14 volt. I forgot to measure it with cold engine.

Please, show me which one you mean ;)

Thanx, Andreas

barge master
10-21-04, 04:45 AM
The wire in #1 is your choke wire. It won't have power unless the engine is actually running though. It gets its power through the oil pressure switch, so unless the switch sees oil pressure the choke won't open properly.
When the engine is ice cold, pull the air cleaner lid and push the accelerator once or twice. The choke should snap shut immediatly.

10-21-04, 06:25 PM

When engine is ice cold, the choke is fully closed.
Once I manage to start it after 10 seconds on starter (it helps to pump with gas pedal), the choke is immediately fully open.

I got a book now, it sais that it should open slowly. How slowly is that? a few seconds or a few minutes?

10-22-04, 12:49 AM
Few minutes would be about right, seconds no. The choke is likely maladjusted. What that wire is for on electric chokes is a heater located in the little round housing on your carb. Also in the housing is a bi-metal clock spring similar to one you would see if you took apart a house thermostat, or the non electric choke on an older car with a mechanical automatic choke. Thats also the reason it is run through the oil pressure switch, so if for whatever reason you leave your key on, then decide to start your cold engine, the choke will still work as intended. You will find some sort of adjustment on that round housing where the choke wire plugs into, possibly even by rotating the entire housing. You will see markings indicating leaner and richer. Make note (a polaroid would be a good idea) of what it is set to currently, and turn it to the richer side. If there are graduations (little lines) try turning it about 2-3 lines and see if you notice an improvement. This is a sensitive adjustment, a little goes a long way, much like ignition timing. If there is no change, good or bad, set it back to the original position.

barge master
10-22-04, 05:07 AM
Huh Dave, I'm wondering if his pulloff is cracking the choke too much? The electrics often have an index mark, and will only install in one spot. I'd wonder if the choke would close completely at all if it was that far out of whack.

10-22-04, 11:00 PM
Good thought. Refresh my memory here, the pulloff is tied in with the front dashpot on the passenger side, the one that is also to the secondary vacuum lockout correct? (kinda) Remembering how it works, but how would you adjust that? :hmm:

Night Wolf
10-23-04, 11:03 PM
yeah, pic #1 is what I was talking aobut....

... When I took mine off before the engine was started, and while it ran, there was no difference... the metal connection looks corrodied.. maybe it isn't making a good connection?

When my enigne is cold, the carb acts funny... anytime you give it 2/3 throttle, it'll shutter, go futher and it'tt sputter, floor it and it'll backfire then stall... it takes a good 10 minutes for it to start acting normal...

What could this be? choke problem? it is only when the engine is cold.. my friend that was behind me said that when I hit the gas, black smoke came out of the tail pipe... that would be burning too rich, right?

is there a way i can disable the choke all together? when I removed the wire in picture #1, it made no difference... still sputter and stuff...

I think it is either a chome problem, or the secondaries aren't opening correctly... I ope the carb dosn't need a rebuild though... but could anyone get more specific with what the problem may be?

barge master
10-24-04, 08:23 AM
Yeah Dave, the pulloff on the front of the carb is what cracks the choke on initial start-up. It's proper name is the primary choke pull-off. There is a screw on it which adjusts a tab that contacts the choke linkage.
General info is that when you set the choke by pumping the pedal, the tension of the thermostat spring {the round disc with the wire}, should decisively snap the choke shut. This should only be checked when the engine is ice cold, like in the morning.
When you crank the engine it should start, and once it does, the pull-off should crack the choke open roughly a 1/4 inch. If it doesn't, and the choke stays closed, the engine will load up and smoke black and chug.
At this point the tension of the t-stat, which has not fully opened,will prevent the choke from opening further. As electricity causes the coil to warm and expand, the choke will gradually open. The choke should not be open for at least a few minutes depending on the temperature.
Unless it's a really warm summer morning, the car usually won't start well unless the choke closes completely. The position of the choke also controls the cam position for the fast idle, so if the choke doesn't open or close properly that will be affected as well.
You will often hear guys say to put a piece of hose on a pull-off and suck on it to see if it moves the lever as a means of testing it. What you really need to find out for sure is to put a vacuum gun on it and see if it HOLDS vacuum. A lot of times the lever still moves, but if you put continuous vacuum to it, you find it leaks down,and is causing a vacuum leak.
Hope this helps you choke troubled guys. :hmm:

10-25-04, 09:33 PM
AS far as the choke setting it should be on 2 ritch. That means the black thing with the spring on it held in by the three screws should have a little marking line on it, and that line should be pointing to the second left from middle dot on the metal housing. Thats the proper setting, maybe yours is tuned different so the mixture should be different.

10-29-04, 07:47 PM
Well... I Think I was wrong about the choke. I have studied it closely now, and it's acting as supposed.

Still hard to start when ice cold. But pumping the pedal several times before starting helps a lot. So I think I can live with that...

Thanx guys!

10-31-04, 08:38 AM
I think that they should have caught this, and they might have, but did they replace the coolant temp sensor. It is rare, but that can cause a hard to start condition.

10-31-04, 04:21 PM
No, I dont think so.
I've read that one can replace the whole carboretor with a "replacement carburetor". I think that would be good. Is it possible to get one? And where? I live in Sweden, and Cadillac is not very common over here :)

12-07-04, 02:35 AM
If you have to pump the accelerator a few times to get it started, then the float level in the carburetor is not set properly and it isn't getting the proper amount of fuel to start through the accelerator pump assembly. I would suggest that you purchase a carburetor rebuild kit and rebuild the entire carburetor. Pay attention to every detail in the instructions that come with the kit and make sure to do each adjustment exactly in the order that the directions say. Carburetors are not difficult to rebuild if you have any mechanical ability and patience to read and follow directions. It will be a worthwhile and rewarding experience that you will be proud to say that you have done it yourself.

12-07-04, 07:52 AM
With engine cold, check the float level. It should be close to it's full level. It wouldn't be uncommon to find it low or even empty because Q-Jets are well-known to have a bowl leak-down issue. That's why most commercially rebuilt ones will have a sealer coated on the bottom of the bowl (on the underside, not inside). I wouldn't scrap a Q-Jet unless it's absolutely neccessary because they're actually a great carb, but they should be rebuilt at approx. 100K mile intervals I've found.