Hi,

I am trying to come to terms with how the Carburator works on an 82 Firebird. I believe that it is a Rochester E2SE on a 2.8L V6 engine. It takes a while to start the car when cold and also have a problem with it cutting out at traffic lights when the engine is hot.

I decided to start with how the choke works and am already confussed with the Air cleaner. I know when the engine is cold that it takes the hot air from the exhaust manifold until the engine heats up then it takes air from the snorkel. On the image below (Air Cleaner sensor) should this be open when the engine is cold allowing vacuum to the Diaphragm spring to close the baffle and take air from the manifold. On my air cleaner this is closed, is this right?

I thought that the temperature sensor inside the air cleaner is operated by the temperature of the carburetor. But there is a second tube coming from it on the bottom of the air cleaner. This has been blocked off for some reason with a plastic screw as can be seen from the picture (Air Cleaner). One tube goes to the Diaphragm to operate the baffle but what is the other tube for.

please Help,
Thanks.

 

That tube goes to a vacuum port to give that temp sensor vac pressure to open and close the baffle. Also if your car has a charcoal canister like my 84 Z28 make sure vacuum is being sent to that as well cause my car was acting like it wanted to stall at any stop sign I came to.

 

Thanks for the reply. I will try find the port on the engine and connect it up. Another point is that the Catalytic converter was removed from the car and the wires from the oxygen sensor cut. This was done sometime before I got the car. I presume that this wouldn't effect the hose on the air cleaner being connected to the vacuum port. I don't understand why it was removed.

Another question about the choke. I see from the wiring diagrams that there is a choke heater. The choke light on the dash comes on while the engine is turning only and not when it is started. Is this heater only on while the engine is turning or is it supposed to be on until the engine heats up.

Thanks.

 

The choke light has to be on while the engine is stopped, and off while it's running. Any other behavior indicates some sort of problem somewhere, although not always with the choke.

If you don't have an O2 sensor, you'll never get it to run well with a stock carb.

 

Okay that is what is happening with the choke light on the dash so that is working properly.

If I connect up the O2 sensors will that work okay the fact that the Calalytic converter is removed will that make a big difference or any?


On the pictures I posted of the air Cleaner there is another tube underneath the air cleaner which is also blocked off. Could some one tell me what this is for and where it is to be connected.

Thanks.

 

The O2 sensor is upstream of the cat. It has no idea if the cat is there or not.

 

Good that it doesn't know it is missing. I am still trying to find where the Two air cleaner hoses go. The other side of the Temperature sensor in the air cleaner goes to vacuum port but where is it. I have taken some pictures. The picture below shows a port with a short piece of Tube and a hex screw stuck in it to block it off. Should the temperature sensor tube go in there but what is that thing in front of it where the coolant hose is. That has two ports with nothing connected.

The other picture is of an EGR valve I think. There is no hose going into that either. From the pictures in my first post of the air cleaner upside down. The hose under the air cleaner where is thak supposed to go. Would it be to this EGR valve.

Thanks.