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Dieseling

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Old May 1, 2007 | 10:00 AM
  #1  
iroc3o5's Avatar
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From: pawtucket ri
Dieseling

i have a 305 with a quadrajunk. i just put in a new heater core, and removed the air conditioning. i fire it up for the first time since the modifications, starts perfectly like always. i let it run while i refill the radiator and stuff, it has been running for about 10 mins, and i go to kick it down, and i cant. the electric choke wont close it seems like. so i shut it off, and it starts dieseling violently, so as fast as i can, i pop the hood, take off the air cleaner, and put my hands over the carb to smother it, and it shut off. that is when i notice this:

the top thing, which i beleive is the choke, is staying open about a 1/4", instead of being closed. i think that is letting the air in fuel into my engine, making it diesel. if i shut the choke with my hands, it will stop dieseling right away, but when i let go of it, it will just pop back open. HELP!!
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Old May 1, 2007 | 10:34 AM
  #2  
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
The choke is supposed to open when the engine is warmed up (such as running for 10 minutes), not close. It is supposed to close when the engine is cold.

What you're describing is a classic symptom of the choke not getting the 12 volts it needs to warm up the choke thermostat. Check the wire that goes to it (round black plastic thing on the passenger side of the carb - your picture doesn't go far enough to allow us to see if the wire is attached).
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Old May 1, 2007 | 11:02 AM
  #3  
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From: pawtucket ri
Re: Dieseling







i found this near the distrubutor, fell off of something

maybe it came from this thing
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Old May 1, 2007 | 11:22 AM
  #4  
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From: pawtucket ri
Re: Dieseling

all that photography, for nothing. i put the smog pump belt back on, and it's fixed...
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Old May 1, 2007 | 12:06 PM
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: Dieseling

How about that vacuum leak in the 4th picture?
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Old May 1, 2007 | 12:15 PM
  #6  
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From: pawtucket ri
Re: Dieseling

Originally Posted by Sonix
How about that vacuum leak in the 4th picture?
excuse me?
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Old May 1, 2007 | 12:24 PM
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: Dieseling

In your fourth pic, front of the carb, looks like a line that's disconnected. Causing a vacuum leak. That probably explains the piece of hose that's disconnected, but i'm not sure what that went to back towards the distributor, EGR area?
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Old May 1, 2007 | 12:32 PM
  #8  
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From: pawtucket ri
Re: Dieseling

oh, that thing in front of the carb that is disconnected... i took the air cleaner off obviously to take the pics, and there is a small hose on the air cleaner that goes there, so i when i take the air cleaner off, i unhook it. good looking out though.
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Old May 4, 2007 | 10:52 AM
  #9  
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From: Lexington, SC
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: Dieseling

the piece you're showing as disconnected appears to be the hard vacuum line for the vac sensor on the driver's side firewall. it should be coming out of the wire harness by the dist where your other picture showed. it should be connected to the carb in the rear where you're showing a normal rubber vac line connected. the rubber line possibly replaces the broken hard plastic original line and still provides connection to the vac sensor. i'd check that.

your dieseling problem is most likely related to the choke keeping idle speed elevated.
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Old May 4, 2007 | 02:02 PM
  #10  
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From: pawtucket ri
Re: Dieseling

dude, i just said it goes to the air cleaner, want me to say it again? it goes to the air cleaner! i re attatched it as soon as i put the air cleaner on? you want a picture?
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Old May 4, 2007 | 02:33 PM
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Originally Posted by iroc3o5
dude, i just said it goes to the air cleaner, want me to say it again? it goes to the air cleaner! i re attatched it as soon as i put the air cleaner on? you want a picture?
Stow the attitude. It doesn't work around here.

He was referring to this:
Originally Posted by iroc3o5
i found this near the distrubutor, fell off of something

[/IMG]
There is a small vacuum port on the rear base of the carb, back by the distributor.
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Old May 4, 2007 | 02:57 PM
  #12  
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From: SC
Re: Dieseling

lmao... getting a 'tude with somebody trying to help...
go fix your nightmare on your own.
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Old May 14, 2007 | 03:41 PM
  #13  
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From: Austin Texas
Car: 1984 Z28 Camaro
Engine: 305 H.O. 72,000 original miles
Transmission: 700R4
Re: Dieseling

Diesiling is caused by a high idle speed, high coolant temp, or leaking carb.
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Old May 14, 2007 | 06:34 PM
  #14  
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From: pawtucket ri
Re: Dieseling

i fixed it.
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Old May 14, 2007 | 06:44 PM
  #15  
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From: Triangle NC
Car: 82 Ponitac Firebird
Engine: 350 TPI
Transmission: 4L60e/TCI TCU
Axle/Gears: 2.73
Re: Dieseling

Gee,
You know I have forgotten how much trouble one can have with an carb. Thank God I converted to fual injection in 98!!!!!
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