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'86 Brougham
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54 Posts
Discussion Starter #1
86 Brougham 307 with a carburetor.
Automatic choke plate is closed (cold) and opens as engine warms!

Hard start and barely runs until warm. Not enough gas. IMHO
How do I check/ replace the vaccuum components?
What else should I look for?

Runs well at operating temp.:helpless:
 

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Hey Chi

Is the choke plate closed all the way? I dont think it should be. I think it should have a slight gap........11/32" or so.

good luck
 

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'86 Brougham
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54 Posts
Discussion Starter #3
Choke plate doesen't close and seal, there's about a 1/4'' opening and then it slowly opens full as the car warms. By the time the choke plate is fully open, the engine is running rather well. I'm thinking vacuum, nothing seems to be "drawing" the fuel during cold start operation.
 

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Hey Chi
Try setting the gap to an 1/8" and see if that helps. I had a 84 Olds that I had to tinker with. It was kinda cold natured too.

Later
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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There are a whole bunch on this board who will sing the carburetors are great song but they can't seem to post any information about servicing one. Makes me wonder. Especially when someone recommends to replace an accelerator pump to fix a secondary bog situation. :cookoo:
Your choke should look completely shut when it gets into cold weather overnight. The gas pedal must first be depressed once in order for the linkage to set itself. When the car starts, the primary choke pull-off has the job of cracking the choke open just a little bit. This is the little vacuum diaphragm located on the passenger front side of the carbonator which is held on with 2 screws and receives manifold vacuum. You will notice the pull-off linkage has a Phillips head screw adjustment. This adjustment varies the amount the choke cracks open when the engine starts. The choke thermostat will open the choke slowly after the engine has been running a few minutes. An easy way to check the primary pull-off is to start the car and see if you can poke the secondary (rear of the carbonator not the front) butterflies open with light finger pressure. If you can then the primary pull-off is either bad or is not receiving a good vacuum signal. Try it first with the engine off. The required pressure to open should increase a whole bunch with it running. When replacing a bad primary pull-off it will be necessary to adjust the choke pull-off angle. There is a tool known as a choke angle gauge that measures exact choke angle for adjustment when rebuilding the whole carbonator or replacing the primary pull-off. You can get away without using one of these with a little patience. What works for me is to either apply vacuum to the pull-off line and pull it in fully using a vacuum pump. I then adjust the Phillips screw on the linkage to open the choke against slight finger pressure in the closed direction. The amount of opening can make the difference between your car starting and stalling out a few times verses running OK when stone cold. Try it so it just cracks the choke open. If you don't have a vacuum pump then do the adjustment by just pushing the linkage in on the pull-off. A service manual would work better than listening to me.
 

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70 Fleetwood, 87 and 90 Brougham, 94 Fleetwood
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215 Posts
The Ape Man said:
There are a whole bunch on this board who will sing the carburetors are great song but they can't seem to post any information about servicing one. Makes me wonder. Especially when someone recommends to replace an accelerator pump to fix a secondary bog situation. :cookoo:

It seems so many have forgotten how to properly service carbs these days, and so many others with a bit of knowledge seem to be experts. It's getting to be a forgotten art in these days of EFI. These were amoung the last carbureted cars GM made. The horrid little Geo Metros being the other holdout.

BTW, that is good sound advice you have given there.

Mike
 

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'86 Brougham
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54 Posts
Discussion Starter #7
I'll say it's good sound advice ! WOW!
Thank you for taking the time to help me!
I thought something was amiss with the vacuum assist.

Why was my post moved? Did I post an engine question in an overall vehicle forum??
For future reference, so I don't do it again; no gripe, just thanks for the info.
 

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'86 Brougham
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54 Posts
Discussion Starter #8
:cool2: Replaced the primary pull-off as suggested and the car starts like a dream.:cool2:

:wave: Many thanks.
 
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