i have a 1987 firebird formula with a 350 4 barrle carb. when i get in it starts right up and idles fine but when it warms up it stalls most every time i come to an idle. also sometimes when i am in a hard accel it will sputter and stall. usually it will start right up after it stalls. i dont know if this is the fuel filter or a sticky choke or something more serious.

 

Welcome aboard thirdgen.org.

3rd gen 350's didn't come from the factory with carbs. So, either a 350 was put under the 305 carb, or a carb was put on the originally-TPI 350, or the TPI 305 was replaced with a carb'd 350.

It would help to know which carb you have, and what the car had originally.

 

i am not sure exactly what it origonally was i just bought the car a couple days ago. i do know it was stock a 305 carburated but the guy changed it to the 350. as far as the carb i would assume it is the same one the car originally had in it but i am not possitive all i know is that it is a four barrel.

 

Okay, I should have given you one more tip - the 8th character of the VIN identifies the engine the factory put in the car. "H" = LG4 305 carb, "F" = LB9 305 TPI, and "8" - L98 350 TPI. Most likely yours is an "H".

I doubt sticky choke, or you would have been talking about high idle when warm. The fuel filter is always a good thing to replace when in doubt. There will be one in the carb inlet (where the fuel line attaches to the carb), and I believe one under the car in front of the left rear tire.

The '87 model year had both a mechanical fuel pump mounted on the engine, and an electric in the fuel tank. Many otherwise knowledgeable mechanics/gear heads don't realize the electric is in the tank, and those pumps are known to be failure prone - since there is a mechanical pump on the engine, the mechanics/gear heads assume there isn't an electric in the tank. When the electric isn't working, it makes it harder for the engine mechanical to keep up. When you turn the key to "on" before starting the engine, can you hear the hum of the electric pump? It won't be louder than your seat belt buzzer (most likely), so make sure you have your seat belt fastened, radio off, and heater fan turned down before you say the electric pump isn't working because you can't hear it.

But, your symptoms don't sound a lot like that. You may need simple carb adjustments to bring everything back to factory settings, or the ignition may need work (spark plugs, plug wires, cap, rotor, etc.). Or, it may be a simple adjustment to the "curb" idle speed, the setting when the engine is warm with the transmission in drive and AC off. Assuming the 350 has a reasonably mild cam, the carb system idles pretty low - 500 RPMs in drive with AC off.

If someone tries to tell you the problem is a 305 carb on a 350, don't listen to them. I've been running a stock factory '86 305 on my daily driver 350 since August 2005.