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Old 03-18-2012, 09:54 PM
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350 buick;tough starts, sputters at part throttle

Hey everyone! I'm looking for advice on a problem with my 76 lesabre. I've done cap rotor plugs wires, fuel pump, and had quadrajet rebuilt. Still same problem, at my wits end. Car starts up in the morning after a couple pumps, then stalls unless I keep pumping it. I have to pump the gas for about a minute then it will idle no problem. Will idle all day long. When I leave the driveway it chugs alittle so I'll pump the gas a little to keep it going until it warms up. But the problem is it always seems to be running inefficiently. I realize these big beasts aren't exactly fuel efficient but I at least want it to run as good as possible! If I floor it it goes no problem, just at cruising speed and slight throttle increase that it has problems. That and the morning start. Any ideas? Could it be problems with the old emmision control crap! Thanks for any advice. Cheers

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Old 03-18-2012, 10:28 PM
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Sounds like your chokes not working right. That'll cause your cold start problems.
Might also be a vacuum leak causing the cruise problem.
Here's a link or two on quadrajets.
http://www.digitalcorvettes.com/foru...ad.php?t=88376
http://www.vetteprojects.com/kstyer/quadrajet.htm
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Old 03-19-2012, 05:37 AM
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Also an important par of the choke system is the choke "unloader". It opens the choke a small set amount after the engine starts to allow it to run cleanly- which it will not do if the choke is closed too far or closed all the way.

This is a vacuum operated pod at the corner of the carb on the passenger side. It can be front or rear-mounted, and may or may not have the secondary air valve also attached to it by linkage.

Check it for proper operation by applying a vacuum (by mouth will work if you add a length of vacuum line so you can reach it). The mechanism should retract w/vacuum and should hold the vacuum you apply.
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Old 03-19-2012, 07:15 AM
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Thanks Guys, There's two of those unloaders, one is brand new the other I'll double check. Then I'll start tracing vaccuum hoses! Gonna take it for a drive today so I'll mess with it a little before hand. Thanks for those links too RENUTS. Haven't had a chance to go through them yet but will. Cheers!
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Old 03-20-2012, 07:34 PM
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I think we're on the right track regarding the choke. I played with the primary choke plate when I started it this morning and it had a direct effect on how it ran when it was cold. I've got an electric choke that I picked up a while ago and attempted to install it today but I couldn't get it to work. If I apply power to it, shouldn't the choke close when cold? It didn't move at all. So I took it off and put 12v to it and nothing happened. Just wondering wouldn't the spring recoil or at least move one way or another if I apply direct power to it?
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Old 03-21-2012, 12:36 AM
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Quote:
Originally Posted by malibusimon
I think we're on the right track regarding the choke. I played with the primary choke plate when I started it this morning and it had a direct effect on how it ran when it was cold. I've got an electric choke that I picked up a while ago and attempted to install it today but I couldn't get it to work. If I apply power to it, shouldn't the choke close when cold? It didn't move at all. So I took it off and put 12v to it and nothing happened. Just wondering wouldn't the spring recoil or at least move one way or another if I apply direct power to it?
The electric choke coil/heater assembly should heat up after just a few seconds and after 2-3 minutes it should open the choke, providing the electric choke itself is good, and the choke shaft and linkage/fast idle cam, etc. are as they should be.

The electric choke assembly needs a ground to the metal on the back side; it grounds through the carb/choke housing to the carb, intake, block and eventually to the battery, so the connection of the choke coil/heater assembly to the choke housing has to be tight- or add an additional ground wire. If there's still a gasket in the choke housing from when it was a hot air choke, remove the gasket.

Electric chokes will go bad, so if you hooked the choke up to the battery using jumpers and you see no movement of the coil, and there's no heating of the center stud the coil mounts to- it's bad. You can check the resistance, as well.

More HERE.
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