As the title says, what are the signs of a bad carb. My girlfriends brother in law has a 87 trans am with the digital dash and all and the quad carb and the thing hasn't run in years. When he first had problems they told him it was a bad carb but he didn't have the money to fix it at the time. So I went out and looked at it today and when he tried firing it up it wanted to start and did for like half a second and then died right out. We used starter fluid and carb cleaner as well. It was also making this weird ticking sound which sound like it was coming from somewhere around the carb when he was trying to start it.

Basically I am not sure if its the carb for sure because I don't want him to have to replace it and have that not be the problem. When he did get it to idle a while ago as soon as he put it in gear it died as well. Any suggestions would be appreciated. Also, does anyone know a good place to get a replacement carb for that car?

Thanks again

Well, that wierd sound you heard was the mixture control solenoid i believe. Thats normal, and should stop after a few seconds if the key is in the on position. The car may just not be starting cause the gas is contaiminated from sitting so long. try putting in some water remover in the tank, or maybe just even drain all the gas out and fill it up with some fresh fuel. Maybe go nuts with some carb and choke cleaner on the throttle blades, and down inside the barrels. I'd even recommmend changing out the fuel filter real quick.

Let me edit this baby some for ya to answer more questions. Check the fuel pressure on this car, like you said, dont condem the carb just by a guess, unless that place that told him it was bad is psychic. If it is indeed the carb, you can find good ones and lots of em at www.summittracing.com. Good luck.

Well first off we put dry gas in it before we started but that really isn't the main problem why its not running right because it had problems before the car sat for the long period of time. We used a lot of carb cleaner to try and get the thing running and still no good. The only other thing that I can think of is that the timing may be off because once or twice while we were trying to start it a puff came back up through the secondary's.....I am kinda at a loss....

Why don't you just do the right thing and start with the basics. If it has sat for a years it's no use trying to get it to run if there is varnish in the carb circuits. Take the carb off and have it rebuilt at a reputable shop or you can just order another. If you put too much dry gas in your fuel tank that will also mess up the fuel composition and too much dry gas can make a engine run awful bad or not run at all. Make sure you have about 10 gal of fresh fuel before trying again. What were the previous problems before he put the car away and let it sit? Just how long has this thing been sitting? Start with the little details before you start messing around with timing and other things. Next thing you know it'll be so messed up you'll land up paying someone big bucks to fix it.

He basically had all of these same problems before it sat which is why it sat for so long. There aren't really any new problems that I know of. It sat for about 3 years or so without really running. He had it running a couple times but like I said it just died off when he put it in gear. What is the price difference between rebuilding the carb he has or getting a new one?

Thanks for the help so far guys

getting the carb rebuilt with a kit does not cost as much as u think. i got mine done for around $125.00 and they took it off and put it back on for me. It was a small shop I know of with a hell of a mechanic.

Regardless of whether or not the car ran right before sitting, you need to go over the rest of the car first. Ignore the carb for now. Check everything like fluids, filters, vacuum hoses, ignition system (remove cap and plugs for inspection), etc. Compression/leakdown tests are optional. Change the gas - just do it and don't argue.

Then if you still have problems, diagnose the carb. 9 times out of 10 a "carb" problem is vacuum or ignition related. You already stated you heard a clicking, which shows the mixture control solenoid circuit is functioning. Even still, a rebuild is probably in order. And although intimidating, its quite simple. There are several books available that detail the carb functions and what to inspect and address during a rebuild. Varnish and carbon buildup in passages is very common after long periods of sitting. Doug Roe's Rochester Carburetors book is highly recommended. Some basic handtools and a some mechanical knowledge is useful. No need to be an expert. I rebuilt and tuned mine nearly dead on the first time with never touching a carb before.

Yea I looked at hte plugs and wires and everything and they all seemed fine since they were done right before the car sat. The only thing that I have checked is the coil and I know for a fact that has never been replaced. I checked all of the vacuum hoses and there were no problems there. I did not replace all of the gas that was in there though, just added some dry gas to what was left. I am pretty sure I would have no problems rebuilding the carb with some guidance because I do have mechanical abilities (did the cam swap in my Z28) but I have just never messed with a carb before so I don't know much about them. Is it worth rebuilding the one he has or should he just get a new one? I already have it off the car so I might as well at least rebuild it while its off or have him get a new one.

A rebuild will cost roughly $50 depending upon carb condition. Carb kits usually run around $25, but you'll need to figure in several cans of carb cleaner, and a few extra dollars for misc items that do go bad that the rebuild kits do not contain. Tuning items like metering rods are highly recommended, DR rods are an excellent choice for the secondaries, and are available at any GM dealer. Secondary metering cams are also a problem, and are available at www.carbs.net , along with many other items. Every car I've run the DR rods in has picked up significant performance over stock. Its a very wise investment for only $20.

BTW - do not tamper with the primary side of the carb. It is completely computer controlled, and will never work correctly if jets or rods are changed. Set all adjustements according to instructions in the rebuild kit. All performance mods/tuning should be focused on the secondary system. www.thirdgen.org has a forum specifically dedicated to carbs, and will have all the info you need, plus much much more.

A rebuilt carb will cost several hundred dollars, and is still no guarantee that it will cure your problems. You're still basically guessing at the carb.

Clicking is definitely the mixture control solenoid. Total normal- and a good "sign of life."

Agreed- you're guessing at the carb. A simple thing like the choke vacuum pull-off canister on the pass. side of the carb being bad (very common) can cause problems like that. Fires right up, then dies and won't try to restart (hint: becuase the engine is now flooded and no amount of starting fluid is gonna get it fired up until it sits for a while).

Try this- hold the choke plate open MANUALLY and shoot some starting fluid down the venturis. Fire it up. It should fire instantly and keep running for a little longer than it did before. Before it dies, you can then MANUALLY close the choke a little more to keep it rich enough to run on a cold engine. As it warms up you can open it a little more, a little more, a little more until it's fully open.

Choke-related problems on the QJet are FAR more common than internal malfunctions. And they can make it a bear to keep a cold engine running.

If it seems you're on the right track trying this, shoot me an email and I'll let you know how to diagnose and fix the most common QJet choke problems.

Ummm... No.