: Interesting behavior; Pesky q-jet



7.0,hellyeah
10-14-04, 12:43 AM
I replaced my orig, quadra with another quadra I rebuilt while I rebuilt my original. My original was filled with oil and carbon along the various channels etc. I can't believe it even ran. It started right up after I pumped the gas once or twice and ran just fine as usual, a little better response though. Recently I was driving and I gunned the crap outta it and layed a little rubber while doing about 15 behind a slow truck. Suddently it started surging a buch, really surging. I pulled into a parking lot and opened up the hood. After gunning it for a second it began to run smoothly. I don't really know what would cause that. Another thing its doing is idling high. I know it aint the idle because the idle does drop quite a bit to normal on occasion. It seems its Idling at warm up speeds after its already warmed up. What else could it be? :banghead:

sizanjdf
10-14-04, 03:50 AM
I feel ur pain...I just rebuilt the carb on my 77 and it ran great for a few minutes, but was idling way to high. got it to idle down and then it wouldnt run worth a crap. It seems to be leaking fuel out around the accelerator pump or something, Im at a complete loss...so if you find anything out let me know!

davesdeville
10-14-04, 05:08 AM
Have you done the same thing with the old carb and had it not surge? And have you checked your fuel pressure?

barge master
10-14-04, 03:37 PM
There are 2 metering rods inside which are held shut against spring pressure by engine vacuum. As the throttle is opened, and vacuum drops, a spring lifts the rods, allowing more fuel into the engine. Sometimes they can stick on an old,dirty carb. The needle and seat could be getting little hunks of crud stuck in there from time to time as well.

7.0,hellyeah
10-14-04, 10:50 PM
The surging was a one time deal. Now it idles a little high. I can get under the hood and push the throttle arm back and the idle will drop, but the pressure I'm exherting on it is almost bending the arm. I know what you mean about the rods getting stuck but I dont think thats the problem. When that happens you can usually floor it and let off and the throttle will drop because you shook the needles to the point where they came loose. I thought maybe it was the choke, so I took the cover off and made sure it was on the correct +2 rich setting. It was all fine. Another thing is that I removed the a/c solenoid that increases the throttle when the a/c is on. That should only increase the throttle though right? The cable from the cruise controll feels a bit tight but it isn't the cause I dont think. I took it off the valve covers but the idle didn't drop. I'm worrying about the engine overheating in traffic. Please help! :worship:

DaveSmed
10-15-04, 12:28 AM
Is it resting on the min. idle screw when fully warmed up? The screw is located on the drivers side IIRC. Your fast idle cam could be getting stuck too.

barge master
10-15-04, 05:37 AM
Hmmm. No vacuum leaks anywhere huh?

7.0,hellyeah
10-18-04, 12:25 AM
well i got frustrated and took the the other carb from a '77 sedan deville and slapped it on my '79 coupe. Same carb pretty much. Its idle was high too. I adjusted the fast idle(I think thats the right name) in the choke linkage. It dropped the idle perfecly to a good level. The engine isnt bouncing like it should. Instead its running weakly with little pop at all. When you step on it its fine, but at Idle its runs funky. Maybe its lean. I dont know if the left or right screw adjusts gas level. When the gas is depressed, then let off, it stays at high RPM's unless the gas is released very quickly. I dunno. I just think that the engine should be shaking more at idle. I'm going to try the original carb again but adjust the farst idle lower. Its weird how the '77 carb gets stuck. Another thing it doess is surges when cruising along. Just a little but is noticable. :drinker

7.0,hellyeah
10-19-04, 03:44 PM
It seems like the snag thats keeps the idle high after letting the gas off is coming from the inside of the carb. I removed and cleaned the primary butterflies when I rebuild the carb. Maybe they go moved a little and are rubbing, is that a feasable possibility or should I be looking for another linkage issue. I would also think this to be the culprit because the throttle arm isn't contacting the slow idle screw on the right side of the carb. Any suggestions?