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Author Topic: backfiring  (Read 10115 times)

Offline gold84gmc

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backfiring
« on: August 30, 2007, 03:24:28 pm »
ok, so i ran the truck today and let it get to operating temp. and a couple of times when i gave it a quick rev it backfired out of the carb...and a couple of times outa the exhaust.....does this sound like the timing is off to you?
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92 buick century custom 3.3L

Offline VileZambonie

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Re: backfiring
« Reply #1 on: August 30, 2007, 03:33:45 pm »
either that or your firing order is incorrect. Make sure no vacuum leaks and the choke is adjusted properly
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Offline gold84gmc

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Re: backfiring
« Reply #2 on: August 30, 2007, 06:23:34 pm »
alright, i checked the plug wires, and they are in the correct order.
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Offline stefjeano

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Re: backfiring
« Reply #3 on: August 31, 2007, 07:58:15 am »
Your cam might be going bad!
I will get worst!
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Offline VileZambonie

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Re: backfiring
« Reply #4 on: August 31, 2007, 02:09:30 pm »
What about the choke and vacuum leaks? Did you check? Is it only if you snap the throttle?
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline gold84gmc

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Re: backfiring
« Reply #5 on: August 31, 2007, 03:01:22 pm »
yea its only when i snap the throttle. i kno there is a few vacum lines that seem loose.
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Offline j-dub-u

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Re: backfiring
« Reply #6 on: September 01, 2007, 08:25:52 am »
Sounds lean to me.....and since it only happens when you snap the throttle, could be a busted diaphram on the acc. pump.  ???
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Offline gold84gmc

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Re: backfiring
« Reply #7 on: September 01, 2007, 11:22:58 am »
any way i would be able to figure out if its the acc pump without tearing the carb apart?....what is it anyways, a q-jet? (its the factory 4 bbl)
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Offline VileZambonie

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Re: backfiring
« Reply #8 on: September 01, 2007, 02:07:22 pm »
The factory 4 barrel was a Rochester Quadrajet. If you depress the accelerator pump plunger all the way down with the engine idling it should stall the engine if it's working correctly. That's a quick ez check. Check around for vacuum leaks
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline gold84gmc

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Re: backfiring
« Reply #9 on: September 01, 2007, 03:33:39 pm »
http://dyeager535.topcities.com/CCCqjetdiagram.html   ...anyone know what part in the diagram is the acc pump?
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Offline gold84gmc

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Re: backfiring
« Reply #10 on: September 01, 2007, 03:36:21 pm »
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Offline DnStClr

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Re: backfiring
« Reply #11 on: September 01, 2007, 05:58:09 pm »
yes. That's the plunger.
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Offline gold84gmc

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Re: backfiring
« Reply #12 on: September 02, 2007, 11:26:39 am »
ok so i pushed down on the plunger and the engine revved up as if i had pushed on the gas pedal.
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Offline VileZambonie

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Re: backfiring
« Reply #13 on: September 02, 2007, 03:04:31 pm »
You only depressed the plunger right? You must have some serious vacuum leaks.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline gold84gmc

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Re: backfiring
« Reply #14 on: September 02, 2007, 03:46:25 pm »
oh, am i supposed to push down only on the pin thing, not on the "rocker" thing?
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