Hi everyone, I have an 85 Firebird Trans Am with the 305 and an Edelbrock electric choke carb. When the weather gets cold (40 or below) and it sits even overnight, it won't fire. It turns over until the battery goes dead but it never fires. When it's not terribly cold I can do the screwdriver in the carb trick and it will fire. I've checked all the common non-starting issues such as air, gas and spark. All of those check out. This happened last year when it got cold as well. Any other ideas?

 

You said that air, gas, and spark have all checked out good, so I'm going to take your word for it. Assuming there are no issues in these departments:

Does the engine "cough" or choke when you hit the accelerator from a dead stop?

Also ...

Have you tried spraying some start-up fluid down the carb or have you tried pouring a little gasoline into the carb on the these cold mornings? Try this, first. (I'm assuming that you've pumped the accelerator several times while trying to crank the engine and nothing is happening. Although you have pumped the accelerator, try using start-up fluid or pouring a little gas down the carb, anyway. If someone else is starting the engine after you do this, don't stand over the carb to watch to see what happens. If it backfires for some odd reason, you'll lose a few nose-hairs and a few other hairs.)

If it fires right up after you try that, then I'll comment further.

 

I replaced all the spark plugs (just in case) because spraying start-up fluid didn't make any difference at all. It will just crank and crank until the battery dies. I don't have any problems with it at all when it's running.

After the new spark plugs, it still wouldn't fire. We sprayed start up fluid and adjusted the timing (?) at the distributor and it finally fired right up. Now the test will be if it starts again when it's sat for a bit and/or is cold.

 

If it finally fired right up, it may have taken a bit for the startup fluid to make its way to the combustion chambers. I usually open the throttle plates and pour a little gas right down in it. I know that, with the 305's, if it isn't getting a sufficient amount of fuel down into the intake, it's not going to fire.

I had a similar issue. Only did it in the extreme cold. It would fire right up after I poured a little gas straight into the carb. Come to find out it was the accelerator pump not squirting enough gas into the nozzles.

That's why I also asked if it coughs or chokes when you take off from a dead start. An accelerator pump will cause that, also.

If it finally started and you were sure beforehand that it's getting spark, then it sounds like a fuel delivery issue. If it does it again, spray the startup fluid straight down into the carb with the throttle open and see what happens.

Another thing to check is your float level to see if the bowl is emptying while sitting.

Usually, if there's fuel in the bowl and you pump it several times, it should be squirting a good stream of gas onto those nozzles. Did you check to see if that's happening?

 

I did make sure there was fuel delivery from the bowl. Now all I can do is wait to see what happens tomorrow morning (suppose to be 28 tonight). I'll let you know. Thanks for the help.

 

"Screwdriver in the carb" as in holding the choke plate open? If so, it may be flooding. When starting a cold carbureted engine, ONE full actuation of the accelerator to provide a pump shot and set the choke is usually all that is necessary.