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Old 09-10-2012, 01:19 PM
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hard hot start, white smoke smells like gas

I have an 84 Z28 with a non computer controlled quadrajet. It starts fine in the morning, tap the key and it fires and there's no smoke at all. If I drive it and let it sit for more than 10 minutes then it will not start unless the pedal is to the floor. A lot of white smoke comes out of the tailpipes when it does fire up. I am not losing any coolant or oil. Any help is appreciated.

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Old 09-10-2012, 01:44 PM
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hard hot start, white smoke smells like gas

After you turn off the ignition. Check the carburetor to see if gas is dripping inside. Sounds like time for a rebuild.
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Old 09-11-2012, 12:25 PM
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The carb is a rebuilt one from an ebay store. I did not see any gas leaking in but I did see some fuel vapor/white puff of smoke coming out by the choke blade
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Old 09-11-2012, 01:30 PM
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Your Qjet has a spring that pushes the choke closed even if the car is warm as soon you shut the motor.
It sit right in front the choke diaphram. Remove it. It's causing the carb to flood.
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Old 09-11-2012, 04:14 PM
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Could you explain what the spring's purpose is? Or does it just push the choke closed. What would happen when it sits over night and I try to start it in the morning? Would the choke still be open?
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Old 09-11-2012, 05:36 PM
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Choke is open in the morning till you step on the gas. Then it closes and sets the choke high idle in to place. When you fire up the motor the choke pull off opens the choke blade about 1/4 inch. As it warms up the choke blade slowly opens and when you tap the gas the choke drops out of place and your motor idles at it's normal setting.
A choke that stays partially closed doesn't make it flood. It makes it run exremely rich.
Something stuck in the needle/seat makes it flood. Or a sunk float makes it flood.
Like cdminter said. Could be rebuild time or take it apart to see what's in the needle/seat.
Here's a link on quads. Explains everything in there.
Quadrajet Info by Lars - Corvette Forum : DigitalCorvettes.com Corvette Forums
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Old 09-11-2012, 06:39 PM
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I did not mention the spring that control the choke with temperature. There is a tiny coil like spring that the minute you shut the engine it shut the choke closed right away. Even if the motor is very hot.
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Old 09-11-2012, 06:42 PM
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If the motor is very hot and the choke is set right then the choke won't even move. If the choke is adjusted too rich it will close a bit and might even set up on the high idle.
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Old 09-11-2012, 07:06 PM
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One note: Not all Qjets use the spring. The one that the choke stays open after you shut a hot engine does not have the spring. That is way it suppose to work. As it cools slowly the choke flap will close slowly.

Last edited by lg1969; 09-11-2012 at 07:12 PM.
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Old 09-11-2012, 07:19 PM
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Please note:
All quadrajets use a spring. Actually a bi-metal coil. Whether in a choke stove attached to the intake or in a housing attached to the carb in a hot-air choke or an electric style that uses 12 volts to heat the coil.
And none will close slowly when it's hot until you step on the gas pedal and release the choke lock out.
Tag!! You're it!!
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Old 09-11-2012, 08:03 PM
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Quote:
Originally Posted by lg1969 View Post
Your Qjet has a spring that pushes the choke closed even if the car is warm as soon you shut the motor.
It sit right in front the choke diaphram. Remove it. It's causing the carb to flood.
Say what?

Please 'splain further.
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Old 09-11-2012, 08:24 PM
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Sorry for the confusion, It's not the bi-metal I'm writing about. A while back I bought a new Q jet for a 350 69 Caprice. The minute I shut the car off and try to start it later, it would shudder and smoke at tail pipe and smell of gas. It started fine when it was cold. It had that little coil spring . I grab a needle nose and removed it. My old Q jet did not have that spring so the choke would stay open when the motor was hot. It would start up right away. A friend cross the street had the same thing his Chevy 2 barrel dual jet, and could not start it once it was hot. He also removed the spring when I told him. After that it started with no problem.
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Old 09-11-2012, 09:26 PM
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OK
You got a pic of what you're talking about.
All I can think of is the choke pull off spring.
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Old 09-11-2012, 09:40 PM
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That's it! The one that sits right behind the choke pull off.

Last edited by lg1969; 09-11-2012 at 09:57 PM.
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Old 09-11-2012, 10:20 PM
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Thanks!
I don't know why it would do that. I'll ponder it a bit.
Only reason I was in clarify mode was I was concerned we might confuse the OP too much.
My apoligies to the OP for jackin' his thread and apoligies to you lg for the rant.
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