Metallica383

OK heres the deal I have a computer controlled Quadrajet running in my car at this time the plug which has wires coming out of it that plugs into the passenger side when plugged in it makes the throttle stick but when I unplug it it runs to rich and floods and stalls about 45 to 50 mph what can I do as of now i am in the process of building a new engine and dont want to was time putting another carb on. So does this one need rebuilt or what?
thanks

Damon

Let's try this one more time with more details. I think we can probably steer you in the right direction but I'm just not getting the whole picture. Feel free to fill the screen. The more details the better.


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94 Firebird Formula M6- No options but Z rated tires. No mods over $10. 13.5@105.
79 Malibu "beater" w/junkyard 400 SBC, tweaked QJet 4bbl, finally a decent set of heads, a few other tricks. A maddening 13.000001 @ 108 on the motor with little traction. No nitrous runs with the new heads yet.
Grandma's old 78 Malibu (33K miles!) soon to have the powertrain from the 79 put in it.

"One of the last remaining QJet tuners on Planet Earth!"

Metallica383

OK the deal is the electronic controlled carb has sevral electric plugs going into the carb I am unsure of how many exactly. But the car started running bad so I tuned it up with the usual spark plugs,wires,distributor,rotor,fuel filter. Well the definition of running bad is that it seemed to run rich and cut out and stall at all different speeds well i talked to a guy who said that he had the same trouble out of his electronic quadrajet and he showed me a plug and told me to unplug it well I did he also told me that this would only work for a while before it started acting up again he said i would have to replace the carb well after unhooking the plug it seemed to run pretty good got worse MPG it seemed and it idles fast so about 3 months later it started hesitating on take off and cutting out so I cleaned the carb and decieded to plug it back in well it ran ok but not quite right but the MPG improved or seemed to but after a week of being plugged back in I was going down a steep hill and and the gas kept increasing not like when your pedal gets stuck it was like gas was being controlled by something else so I stopped the car and tried to turn it off then it didnt want to die it tried to keep running so after it finally stopped I unhooked the plug once more and I am back to very poor gas mileage and I am clueless.

Ed Maher

The thing you keep unplugging is the MCS (mixture control solenoid.) Driving with it unhooked is absolutely barbarian, of course your gas mileage sucks, you're running richer than full rich. Also of note, it can not control your throttle, so it cannot speed you up either.
At this point, i would be willing to bet you have ignored the original problem while causing another really bad one. by driving with the MCS unplugged, you have been running WAY TOO RICH. This has completely carboned up your pistons, heads, valves. When you plugged it back in the other day it kept running and didn't want to shut off cuz it was dieseling, pre-igniting on all that built up carbon. It didn't do this with it unplugged cuz the mixture was so rich that it was burning too cool. Now that it is running in a more normal A/F ratio it is hot enough to diesel.
That speeding up effect you noticed was probbaly normal, just the engine actually running with some power after you getting used to it being ridiculously over-rich.
Where to start. Back to the original problem. You need to get everything working correctly. Your original problem sounds like a bad TPS and/or ignition problems (yeah, this is my explanation for everything, CCCS is so simple that these are the only things that generally matter.) After these check out, you'll probbaly need to replace your O2 sensor as it is no doubt fouled to death from running like this (same with your plugs.) Also, i notice you didn't complain about the SES light, running with the MCS unplugged will definitely set a code, so your bulb is probably burnt out if it isn't constantly lit while driving like that.
One way or another you are gonna need to get your car running in closed loop again. Then, once that is all tuned right, you're gonna want to invest in some good fuel system cleaner and go driving for a few hundred miles at high speed to get the insides of your engine cleaned up. There are other ways of removing built up carbon, but this is the easiest.
...ed

rich40

I have a simular problem, but, my '83 Firebird wont idle good unless I remove a vaccum line. With all lines on, it idles real rough. I just did a major tuneup, but after I cleaned the carb with spray on cleaner, it hasnt idled good since. When I take off at hard throttle, a ton of black smoke pours out. The choke seems to be ok, but not too sure. I hate to experiment with it, I use it for work. Are there any adjustments I can make to the carb to keep it from "black" smoking ???? Thanks !

rich40

I also get horrible mileage.....about 13mpg hwy.......with a stock 305, 4bbl, a/od.....Yikes !!

Metallica383

I get the close to the same mileage and what I am running now it is just a 305 stock with a 4 barrel. I have plugged it back in but it still dont run right and what caused the problem to begin with that i had to unplug it any way was it the O2 sensor gone bad or was it the mixture control thing what step do i take to solve the problem?
Thanks

Damon

Hmmmmm...... Ed covered a lot of ground and I can't really add too much. I definitely second the idea of replacing that O2 sensor just as a matter of principle (I consider it a basic tune up part just like plugs and wires). I also agree with Ed that you need to see what's up with that SES light- it should come on as the engine is starting but then go out immediately after the engien starts. If it's not working then you may never know you have trouble codes stored in the ECM (that could help A LOT with diagnosing the problem further).

Anyways, if the thing runs OK unless you unplug a vacuum line then something might be wrong with the vacuum hose routing. Check the sticker under the hood and make sure ALL the vacuum lines are plugged into what they should be plugged into. If that doesn't help then maybe you actually have something HARDWARE-wise that has gone bad.

A few months back there was a problem with bad idling- sometimes good, sometimes bad usually acting like a rich condition. Turned out in that case that the evaporative emissions system had gone bad and was allowing captured fuel vapors from the charcoal canister to be admitted into the engine at inappropriate times (like at slow idle speeds).

Also, the EGR system is often suspect when you get weird/intermittent idling problems. Does this mean the probablem definitely ISN'T the carb? No. But remember the golden rule- it's ALMOST NEVER the carb's fault. And rebuilt E-QJets aren't cheap.

Wish I could be more specific but you have a ways to go in diagnosing this before I could get to the point where I could say anything with certainty.

Metallica383

Ok sounds to me like I would be way ahead to just remove the electronic quadrajet and replace it with a non computer controlled quadrajet and a vaccum advance distributor and that way I would not run into shooting code problems besides all the pollution stuff is off the car I dont know if and how this may effect the problem I am having it may not I am unsure.
Thanks

86sqarebody

I know im out of place here I have a 1986 k10 has a 262 with a electronic quadrajet the issue im having is similar to what I have been reading on here so hopefully you guys can help me out. truck had been sitting about 6 years before I bought it got it running seemed to have a fuel issue cutting out/hesitation upon acceleration, I did a tune up cat, o2 sensor, plugs, wires, egr, and a gasket kit for the carb, put it back on and issue still present a buddy of mine owns a scanner and we found out the tps was bad so I replaced that but problem is still there I originally was able to drive the truck but could not get above 45 mph without it cutting out like I is running out of fuel, but the more I drive the truck the worse it is getting, now I cannot get above 25mph, what is puzzling me the most is it acts like its not getting enough fuel the engine cuts out and exhaust sound muffled but im getting a rich mixture code, I noticed when the motor bogged/cut out if I put my foot in the throttle the engine will not get above 1500 rpm and I get the muffled exhaust sound, new cat like I mentioned earlier I have not found any exhaust restrictions im out of ideas. any help in getting in the right direction is greatly appreciated thanks in advance.....squarebody

Damon

Holy old posts, Batman! This one is from FIFTEEN YEARS AGO!

Thank you for making me feel old re-reading stuff I typed back when I had a lot more hair and a lot fewer wrinkles.

How does your Blazer happen to come by having a 262 with a cc_QJet on it? 262 never came with a cc-QJet and definitely not in a Blazer. I bet there's a story behind this.

Anyway, you probably ARE running out of fuel. Plugged fuel filter or line, weak fuel pump.... who knows after sitting for 6 years. More plugged up it gets, the lower the speed before it starts having problems. That would be my best guess not knowing anything else.

Fast355

iTrader: (2)

ACTUALLY...The 4.3 DID come with a CCC Q-Jet in some applications. California emissions Astro/Safari van comes to mind. I pulled the timing map out of a 1983 G20 305 with the CCC system and had a buddy that had an 85 K5 Blazer with a factory CCC Q-jet fed 350.

I would actually expect a K10 to have a mechanical Q-Jet with a dual capacity accelerator pump. Does the carb in question have the 3 wire TPS sensor in the front near the accelerator pump cam?? Does the distributor have vacuum and centrifical advance?

Damon

Yeah, I'm with Fast on this one. I'm thinking dual capacity accelerator pump QJet, not a full-on computer-controlled QJet (they look nearly identical at a quick glance).

Posting up a quick pic would tell the tale.

Brother Al

Yep, '86 was an oddball year for the C/K trucks... there was a 4.3, 305, & 350 available with the E4ME Q-Jet. They are not very common however. I have seen one K10 with an E4ME atop its 350 here in a Massachusetts a number of years ago... it wouldnt surprise me if a "Light Duty" K10 had them... likely similar to the suspension set-ups on the "Heavy Half Ton", "Light Duty 3/4 Ton", & "Heavy Duty 3/4 Ton"...

The only real issue with the E4ME Q-Jet was the owner, or "mechanic", that "worked on them", but didnt have a clue about how they actually worked...(or never bothered to maintain them)
Yup...just unplug this, plug up those vacuum lines, & punch those factory mixture screw plugs because it must be out of tune.

A ton of 3rd Gens, G Body's, and B Body's all died premature deaths because of it.