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Discussion Starter · #1 ·
I have a quadrajet that was setup for all the emitions stuff but all the stuff has been taken off teh truck so all the lines are plugged and whatnot. Lately, especially when I put my foot in it, you can really smell gas bad and even just highway cruising you can get a whiff of gas every now and then, plus the 305 its on should get better than 8-10 mpg I hope. I was wondering if anyone knew how to adjust the fuel input on a quadrajet, I just don't want to start trying things then mess something up worse since the carb is already very tuchy. Any help is greatly appreciated. Thank you.


'86 GMC 4x4 Shortbox SS
http://mnorby.virtualave.net
 
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Discussion Starter · #2 ·
First off, make sure all vacuum lines that are unused are plugged off. If this is a regular Q-jet, without feedback, a common problem is the secondary air flap spring gets weak. When you tromp on it, the secondaries open up too soon, and you get a flat spot. This can be checked with the engine off, push open the flap by finger. It should snap back quickly, and take a little pressure to open. If the spring is weak, it can be adjusted by loosening the set screw on the right rear of carb top, and turn the spring.
Second, the float may be set too high. The carb top has to come off to check this.
Third, some Q-jets were prone to cracking in the bottom of the float bowl. Again, the carb must come off and be dissasembled to check. If cracked, it can be repaired with a two part epoxy, or seal-all.
You're best off to buy a rebuild kit (about $25 Canadian), and go at it! Check the throttle body for wear around the primary shaft. A common problem easily solved with a reamer and bushing kit (take it to someone who has one, as the reamer is about $120 Canadian!)
Don't forget to check the basics like plugs, timing, vacuum and mechanical advances.

 
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