Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Quadrajet going WOT
ChrisK7und:
Okay, this is going to sound crazy, but I am at a loss for what is happening. I have a Quadrajet on my ZZ4 350 in my Suburban. On more than one occasion, a light tap of the throttle etc. causes it to go wide open or close to it. It happened to my wife once on her way to the store, she left a red light, started into it and it went WOT. She then got it slowed down by shifting into N and then it was taching out and working the pedal did no good. They shut the key off and finally got it to shut off. Upon restarting it WITHOUT touching the pedal, yep....just idled normal. I thought she was crazy. I then got in it the other day after coming out of the store, turned it over, it started kinda hard so I feathered the throttle and then BAM.....WOT again in Park. I shut it down, DIDN'T touch the pedal to see if the same thing had happened.....same thing, fired up to an Idle......I am at a loss! I can not reproduce this either. I spent a whole day doing FULL throttle starts, driveway redlines, light throttle etc. NOTHING????? Any ideas?
429bbf:
im not cliff the expert. but id say you got more than 1 problem. first how does it run when this doesn't happen? it sounds like your float is to high or the needle and seat stick causing it to over flo slightly .and your throttle plates aren't closing all the way .im talking about the rear ones. its like taking the carb off and feeding it with a spray bottle.the more you spray the faster the engine runs.you may have to wait till the expert (cliff ) responds.
73 Z28:
A couple of things to I'd check would be the spring around the secondary throttle shaft to make sure it's not broken and the throttle return springs to make sure one of them is not broken. If these check out ok, you should cycle the throttle with your hand while observing the carb linkage for any binding on both sides of the carb. If all this checks out ok, you should remove the carb and inspect the base gasket for any rubbing against the throttle blades.
Paul
Cliff Ruggles:
+1 on checking the springs on the secondary throttle shaft. The outer spring may no longer be wound up with the free end engaged correctly on the linkage......Cliff
ChrisK7und:
Thanks guys for the ideas. I have checked the springs on the secondaries and they all look in tact and function just fine when manually opening the secondaries as well as allowing the engine to pull them open etc. I finally gave up and am trying a new Holley Street Avenger 670 on my ZZ4 after a lot of research. I am really not into rebuilding this carb or putting time into it. IF, the Holley doesn't pan out then I will look at ordering a remanufactured QJet from a reliable source etc.
Thanks again for the ideas....
Chris
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