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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: mrzim4 on January 08, 2013, 03:23:47 pm
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I've got an 86 c10 305 with a rebuilt stock carb in it. After my mechanic got it to pass smog, she's been running pretty bad, rough idle, and shuddering whenever I give it gas.
Mechanic wants me to bring it by at 8 AM to work on it (which doesn't work for me since I work nights) and wants to charge me $80 to do it. I've been told by numerous people that the carb is computer controlled, and after looking in there I see no screws to adjust anything (also not exactly used to carbs so I could be completely missing them) I've been told that there is some sort of OBD scanner type of plug in that I need to adjust it but I haven't been able to find anything anywhere. If anyone could give me a hand on adjusting it or finding this tool, that would be great, thanks.
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Is there a big plug on the passenger side top of the carburetor? Does your check engine light come on?
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Going off of a mental image right now, I don't recall a plug on the carburetor, and the check engine light hasn't come on since I fixed the o2 sensor
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There is no OBD plug for a Feedback Qjet. It has a fuel solenoid circuit that adjusts the air/fuel mixture from the O2 sensor signal. If it isn't working correctly it probably just needs to be rebuilt.
There was an article about rebuilding one I will update this post if I find it...
Found it...
http://www.carcraft.com/techarticles/ccrp_0908_qjet_carburetor_rebuild/viewall.html
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A carb rebuild is a little more than I'd be willing to see if I would be able to successfully do..
I guess my question would be, how is it adjusted? The mechanic adjusted it to make it pass smog and I'm taking it in tomorrow to get it to run correctly, I just wonder how they go about doing it
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Same way any other Qjet is adjusted.
Qjet rebuilds are really simple, that article pretty much lays it all out for you.. It sounds like you are having issues with the metering jets, and you will need a Double D tool to disassemble some parts.
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Alright thanks, all I needed to know
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I was talking about the fuel mixture solenoid plug on the carburetor. I've only had one of these and it was on an 87 Camaro. It did have an obd plug under the dash. The fuel mixture solenoid has a stop that is adjusted by the double d tool (I made my own by grinding an old screwdriver). Mine kept coming out of adjustment causing me to get a rich fuel mixture code. I took the air horn off and shimmed the stop adjustment screw with washers so when I tightened it the thing would stay put. Worked like a charm.