Ok guys I have a 69 firebird with a '72 400....go figure. Anyway I just had the carb rebuilt and I am running into cold starting delays. When the car is cold it turns over a few times before it grabs. Once the car is warm it will start right up. If it sits for about 45 minutes, it takes a while to crank again. Not sure if this could be the fuel pump or something more serious like blown rings leaking oil. Let me know if you have any ideas. Thanks for the help.
I doubt it's the fuel pump. usually the motor will run and then die shortly after. check your choke see if it closes when cold and opens properly when warm. if you have a light blue smoke and a strong eye burning smell when running, then the float would be the culpret. it could possibly binding or bad if you did not replace it when rebuilt. the last thing is the adjustment of the air fuel mixture it could be out.
I wish I knew more about carb's. I had it rebuilt by a reliable shop who put an electronic choke, a new vac advance, and checked the carb twice for me after the job. I told them of the fuel smell and they said there was oil leaking through the rings causing the spark plugs to burn oil while the car ws starting. To me that didn't explain the heavy gas smell? Occasionally if the car is hot it will get a puff of white smoke and then run fine. Any ideas?
If you have a Q-jet, you could have the same problem I experienced with one. What you describe sounds exactly what I experienced. When the engine is hot, the fuel in the fuel line between the pump and the carb, and the fuel in the carb bowl will expand from the heat of the engine. I could even hear it "percolating". When it expands it drips through the carb on into the intake manifold, flooding the engine. If you don't let the hot engine sit very long before restarting, it doesn't have time to flood itself. This happens because the design of the carb float/float arm doesn't have as much mechanical advantage as other designs to keep the fuel from going on throught the carb out the jets when the hot fuel builds up pressure. This is how carbking explained it to me. He recommended when you go to start a warm engine that has set for more than a few minutes (and had time to flood) you don't press down on the throttle at all and let the engine crank for a bit before applying a little bit of throttle to get it to start. Effectively what you are doing is pumping the excessivly rich mixture out of the engine when you first go to start the car. I am certainly no expert, but carbking is, and I trust what he said. I hope this is a help to you. If the car runs fine once started, I doubt you have fuel pump problems or more serious internal engine problems.
Ive never had boiling fuel in the lines. mine has a fuel retun line so the gas cools down. how hot does the engine run? Ive always kept it at 160. Even on a hot drive; the temp goes to 180 to 190. that boiling can cause a vapor lock in the carb. rodchester carbs are a pain to deal with. sometimes the screws on the underside will loosen up and that would cause a gas leak which would drive you crazy because you do everything right and still smells rich. to test for this, you wiggle the carb while its on the engine and bolted down. if it moves slightly then the 3 screws are loose. remove it and tighten them down. this could be the cure for you.
What Bruce says about the flooding makes sense. So then if you do what I suggest (crank with the throttle wide open) it will start because the choke won't work with the throttle wide open and there will be no vacuum to suck in more fuel from the carb. The motor will pull in fresh air without added fuel until the air/fuel ratio is right and it will fire.
