Well to start off I have a 1984 Camaro z28 with 96k miles and it has the stock quadrajet on it. I was told by the previous owner that it was rebuilt though.
Well my issue is that when I replaced the fuel filter and it started feeling like it was misfiring or not getting enough fuel so I did a tune up. it had helped it but I ended up having to turn up the idle to 1100 rpms because if it was where it was before it would stall at a red light unless I put it in neutral, and it even stalls sometimes if I would stop real quickly it would stall.
my question is if anybody knows the reason on why it would do this all of a sudden because I have been driving it with the idle at 1100 rpms for a couple months and I would like to find a way to fix it without replacing the carburetor.
Thank you for any help.

 

My stock 86's T/A did that. Never find out the exactly problem. I think it is more of a fuel boiling issue. Is it flooding the engine from time to time?

 

P.S, I have my old carb. It was rebuilt in 2000 when I bought my T/A and I took it off and switched to an Edlebrock in 2002. It has been sitting on my garage shelf since. If you are interested, let me know and make an offer. I am in Columbia, SC

 

It did diesel for awhile but I started putting 93 grade gas in it and it would not diesel anymore.

 

Might want to check your timing. You know when the last time the timing chain and gears were replaced? I know for past experience that a worn timing chain with dieseling can cause the timing to be thrown off.

 

a worn timing chain and gears will retard the cam timing and also pull the distributor timing back... this will make the engine not want to run right, even after you pull the distributor back ahead to where the book says it's supposed to be... a flat cam will also do this- Chevy cams from the mid 70's to the mid 80's are known to gradually go flat over time so that you don't really notice it getting worse and worse until it gets to the point where it runs like crap..

 

To my knowledge the timing chain has never been changed or the camshaft because the car only has 96k on it. it has been bored over so I am not even sure if what has been changed.

 

"Putting the distributor back ... to where the book says it's supposed to be" means using a timing light to set the ignition base timing. Timing chain stretch will be irrelevant.

If the engine was bored over, that's a rebuild operation. To do that without replacing the timing chain is borderline criminal.

You said "tune-up", but you didn't say what that meant. My experience with these carbs is when everything is set where the factory says it's supposed to be, and everything is in working order (including vacuum devices), they start, idle, and run very well.

 

I have made sure that all vaccum hoses are hooked up, but I never have much time because I'm in college. The next thing I was thinking about doing was just replacing all the vaccum lines just to be safe.

 

The #1 cause of carb problems is the ignition system. And, quite often, that's from the timing being set improperly. It isn't hard to set it properly, but it's a little different than what "old timers" are used to, so it is often done wrong.

So, what exactly did you do for this "tune up"?

Are you sure your issues started with the fuel filter replacement? It's really hard to imagine how that could be, unless there was "collateral damage" with that operation. Even then, I wouldn't expect the symptoms you are describing.

 

I did not do a full tune up. I had just done the spark plugs and wires. The only reason I think the fuel filter had anything to do with it was because it literally started messing up right after I changed it. A lot of people I talk to just tell me to get a new carburetor even when they know I want to keep the quadrajet on there. The master tech at pep boys(my work) said that it could have nothing to do with the carburetor, but the fuel pump is just going out slowly. Any ideas on that?

 

A weak fuel pump won't cause a miss at idle. It would show up under power. A fuel pump so weak that it can't keep up at idle wouldn't allow the car to keep moving.

Check your vacuum lines and devices. Make sure nothing got left off when you did the fuel filter. Also make sure the basics are covered, like all of the spark plug wires go to the proper cylinder.

Other than that, the problem showing up when the fuel filter was changed is an incredible coincidence.

 

When I bought my 86 it just didn't run right. I did a tune up and decided to replace the timing chain, gears and dampner. You would not believe how much the OE chain had stretched. The car had only 68K on the engine.

 

It is my experience that when you do something to your car and it immediately doesn't run the same afterwards you should be suspect of the work you just did. I'm assuming you replaced the filter inside the body of the carb? Those are designed to only fit one way and have a check valve on the newer filters. I'm not sure if it would run or not if it was installed backwards, but I would take it apart and check it out. Also there may be an issue with the filter itself, like a flaw at the check valve from the factory wherever its made. Make sure the spring is in the housing right too.
Go buy another one the watch this video

The guy is changing the filter on Edelbrocks version of the Q jet but its the same thing as yours when it comes to the filter. If you notice in the video the guy puts the filter in backwards initially then corrects it places it in right.
Good luck!

 

Well I havnt changed it again yet, but I do remember that when I did I had put it in the right way. I am not 100% sure but I am thinking when I put it in the spring did not push it back out that hard. Is there two springs in there or just one?

 

There is one spring inside the housing.
Like in the photo.....

I don't know what the motor does if there is no spring inside the housing but I'm sure the wizards at GM put it there for a reason. I would guess that unfiltered fuel will go by the filter, and possibly have too much fuel pressure into the carb which may cause a rich condition. ( all theory)

Some of the filters have a one way check valve built into the opening. You should check to see that it opens closes freely with a small screwdriver. It may be screwed up and either close funny or wont open right. If there is too much spring pressure keeping the one way valve closed it will starve the motor for fuel.

 

An issue with the fuel filter should not cause the symptoms described. A fuel restriction would be most evident under power. An improperly installed filter that allowed trash through could jam in the needle/seat and cause carb overflow. Don't see any of that here.

I would verify first that the carb is clicking when the ignition is turned to 'run'. An inadvertent short can blow the engine controls fuse.

I'd next check that the timing is around 20 or so at idle with everything connected and that it advances when the engine is revved.

I'd next check each spark plug and look for one that is different than the rest.

A vacuum leak will cause a high idle.

 

Two observations... (OK, three).....

1. FULL ingition tune-up should include the cap and rotor. They are throw-away parts just as much as the plugs and wires. I've seen them so bad you can't even believe the engine ran at all.

2. Idling is the MOST difficult thing for an engine to do. "Dying" at idle is often caused by a vacuum leak. Under load with some pedal, the amount of air sucked through the leak is negligible compared to the amount flowing through the carb. But at idle the amount of air getting past the vacuum leak can be considerably more than what's flowing through the carb. NO CARB can give an accurate A/F mix if a bunch of air is entering the engine somewhere other than through the carb.

3. You mention the carb was "rebuilt" by the previous owner. That's like nails on a chalkboard to me. ALMOST NOBODY rebuilds a CC-QJet properly. I trust only myself with them (and a few speciality carb shops that know what they're doing). If it was done by your average home-gamer, there's a 90% likelyhood they made it WORSE, not better.