Help! Fuel System Problem
Thread Starter
Advanced
Joined: May 2005
Posts: 82
Likes: 0
From: Arlington Virgina
Help! Fuel System Problem
Hi all, new to these forums and vette ownership! Need some assistance with diagnosing a problem with the fuel system on this vette. It's a 1977 L82 with an Edelbrock 4 barrel carb. Here are the sypmptons - when idling everything is fine; you can tap the gas and get nice throttle response. The problem occurs when i put it in drive and give it a stong tap on the pedal. The engine almost dies, it sputters, makes a popping sound, and you can literally see a a stream of air/liquid mixture shoot out of the side of the carbuerator. Has anyone every senn ANYTHING remotely close to this? Any help would be greatly appreicated. Thanks in advance!
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
It sounds like a weak accelerator pump shot. The gas coming out of the carb. is caused by the positive intake pressure from a lean back-fire in the intake. Be glad you don't have a Holley. They shoot great ***** of fire! 
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Originally Posted by jerrypc
what the h is "Ttt"?
I also
about trying to do some adj before replacing, might get a book or manual on your carb.
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Burning Brakes
Joined: Jul 2000
Posts: 1,162
Likes: 2
From: Beaverton, OR
TT - Do you really think a Holley is more difficult than an Edelbrock? I always thought a Holley was supposed to be the easiest carb to deal with myself. Of course mine still has a couple of hiccups 
big_G - I love those great ***** of fire myself! Only bested (from what I hear) by accidentally activating a nitrous system while the car isn't running and then trying to start the car. . . That one's supposed to produce technicolor hood removals
big_G - I love those great ***** of fire myself! Only bested (from what I hear) by accidentally activating a nitrous system while the car isn't running and then trying to start the car. . . That one's supposed to produce technicolor hood removals
Burning Brakes
Joined: Jul 2000
Posts: 1,162
Likes: 2
From: Beaverton, OR
You are probably right, my Holley was definitely too rich out of the box. I had to step down from 71 to 69 jets on the primary and haven't decided what to do on the secondaries yet. . . If the Edelbrock is closer out of the box it would at least save you that much hassle, but of course the jet changes on a Holley are really pretty easy, just a little messy 
-dath
-dath
Thread Starter
Advanced
Joined: May 2005
Posts: 82
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From: Arlington Virgina
Whoa, i was mistaken I actually have a rochester quadraject carb. Im looking at these two diagrams:
http://www.carburetion.com/Quads/E4MC.htm
http://www.carburetion.com/diags/4mv.jpg
I can't seem to find any reference to accelerator pumps. Could it be called by any other name?
http://www.carburetion.com/Quads/E4MC.htm
http://www.carburetion.com/diags/4mv.jpg
I can't seem to find any reference to accelerator pumps. Could it be called by any other name?
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
Originally Posted by jerrypc
Whoa, i was mistaken I actually have a rochester quadraject carb. Im looking at these two diagrams:
http://www.carburetion.com/Quads/E4MC.htm
http://www.carburetion.com/diags/4mv.jpg
I can't seem to find any reference to accelerator pumps. Could it be called by any other name?
http://www.carburetion.com/Quads/E4MC.htm
http://www.carburetion.com/diags/4mv.jpg
I can't seem to find any reference to accelerator pumps. Could it be called by any other name?
BigBlockk
Later.....
Pro
Joined: Jun 2001
Posts: 672
Likes: 0
From: Quebec
Originally Posted by jerrypc
Whoa, i was mistaken I actually have a rochester quadraject carb. Im looking at these two diagrams:
http://www.carburetion.com/Quads/E4MC.htm
http://www.carburetion.com/diags/4mv.jpg
I can't seem to find any reference to accelerator pumps. Could it be called by any other name?
http://www.carburetion.com/Quads/E4MC.htm
http://www.carburetion.com/diags/4mv.jpg
I can't seem to find any reference to accelerator pumps. Could it be called by any other name?
With the engine off, take the air cleaner off and with your hand turn the throttle linkage to the full open position while checking for two big squirt of fuel in the primaries (front little barrel).
If that's okay then it's probably the famous secondary airvalve spring that is out of adjustement. (That problem is know has quadrabog.) The airvalve is the flap that you see from the top at the secondaries. (rear big barrel) There is a little allen screw under the side (passenger side) at the airvalve shaft. You can see it with a little mirror. That screw secure the spring adjustement that is near the end of the shaft (take a little flat screwdriver to hold it). You need to adjust the spring around 3/4 of a turn after the spring contact the pin. (take a mirror to see it since it's all underside).
I hope I'm clear enough.
Good luck
Stephan
Instructor
Joined: Dec 2001
Posts: 225
Likes: 0
From: League City TX
Originally Posted by big_G
It sounds like a weak accelerator pump shot. The gas coming out of the carb. is caused by the positive intake pressure from a lean back-fire in the intake. Be glad you don't have a Holley. They shoot great ***** of fire!