hi all and thanks for putting together such a great forum. i have an 86 chevy c10 stock 305, with computer controlled quadrajet. the problem i am having is confusing me. first the problem. last sunday the engine started running rough after a stop at a gas station. first thought bad fuel. filled the other tank switched it ran it a little took the carb off cleaned it put it back on. the car will not even pull itself down the road. it idles fine but as soon as throttle is applied it will die.

things i have tried
checked vacuum lines
replaced spark plugs
replaced vacuum/mechanical advance on the distributor
i have great spark
no water in the oil

the engine will studder and miss, going down the road at wot the two rear orifices open and the engine sounds great but there is an obvious lack of power. the question i have is, could the air/fuel mixture sensor be bad? its the only plug on the carb. other carbs i have seen had an additional plug but not this one. i am looking for suggestions on other stuff to check or a way to check this sensor. thanks for the help

86 chevy
stock 305
rochester q-jet cc
accel distributor with vacuum advance.

 

if i had to guess from what you describe sounds like primary metering rods are stuck in closed position.try a few love taps with the magic hammer right near fuel inlet area while engine is running.also listen for mc solenoid clicking...could be stuck and holding rods down.

 

my 84 Z28 had one. i took it off and threw it in the trash. they may lock this thread.

 

thanks for all the advice, finally found the problem was not the carb, but the diaphram in the vacuum advance had went bad. therefore no advance when you hit the throttle, easy fix. however the part was hard to find only online or carquest had the part.

 

lol... You're talking about the carb right? there should be a TGO endorsed Quadra-Junk support group...

 

Those lacking a firm grip on reality are the ones needing the support group. Using a term like "Quadra-Junk" is a clear cry for help.

Case in point:

Wasn't even the carb's fault. Yet there were comments about tossing it into the trash, and derogatory statements about those who work with q-jets.

Making disparaging comments about q-jets won't get a thread locked, but don't assume you'll be able to do so with impunity.

BTW, pdq914, if you have a CC q-jet, you should not be using a vacuum-mechanical advance distributor. Are you sure you have a CC q-jet?

 

i wasn't suggesting throwing a carburetor in the trash. that's just what I did. the cc q-jet is a pain to work on. all the sensors and vac lines must be working properly. i had another carb i put on in it's place and problem solved. my car doesn't have to pass the sniffer test and i don't live in california. all that must be taken into consideration when replacing your carb or doing any engine mod.

 

Well now, then, how bout' I begin by apologizing to those that are enthusiastic about Carbs ...

I should clear something up then, I am talking about electronic QJ... apparently I am not the only one that has had problems with these Carbs... there are posts left and right... the non electrical Carbs I take are worth it... years ago, when I first bought the car, I was ready and at the point of hitting the submit button at Summitracing.com, when I realized that the edelbrock QJ didn't look the same, did some research and sure enough, NOPE... Carb that I needed had to be electronic... I must say I've spent well over 2K on carburetors, off the shelf units, labor, diagnostics, adjustments, rebuilds... no one could get it tuned right, I was buying off the shelf remanufactured carbs from Kragen supplied by Holley for 340 dollars a pop, by the 3rd carb I decided to get one built, this shop was reputable, I spent a little more than 400 dollars... and nope sorry...

My dad has a 75 MonteCarlo and a 76 Trans Am, he still has the OE on the bird, has had it rebuilt many times and each and every time it passes smog and has some pretty good power to it...

 

Dude I gave one away, it was ready to go in the trash, but the person I gave it to was gonna mess around with it and see how they work...

 

My cc q-jet has been the most trouble-free carb I've ever owned (and I've owned a lot of them). I did have issues with Berlinetta #2 when I first got it, even though it had a fresh rebuilt carb on it (beautifully done) with a lot of other new emissions parts on it as well (California car). Choke tied open (even though it worked fine), a bunch of adjustments out of kilter. Wouldn't stay running long enough to go through the emissions test (I wasn't allowed to operate it for the test, of course). I went back home and simply adjusted everything to factory specs; after that it started and ran beautifully, passed the emissions test with flying colors. No problems whatsoever until I pulled it to start the LS1/T56 swap.

I maintain that it's not what these carbs do, but what is done to them that causes all the problems.

Since I read every post on this forum, I can say there are just as many questions about Holleys and Edelbrocks are there are about q-jets.

 

amen to that!