Start up Issues

Okay so I've had my 72 Chevelle Malibu since i was 16, I've been using it day to day to get me to work and school. She has a 2 barrel carb 350 engine, single exhuast, automatic transmission, nothing fancy just an A to B car right now. It's run great for a long time, it still does, the problem recently has been getting her to start. If I drive her every day I usually have no problems, the problems happen when she sits idle for about 36hours give or take a few hours I never actually timed it. Within that time frame she starts up the first time everytime, I have no complaints. Outside of that time frame I have problems.

A few things will happen

1. She starts up, engine idles, engine sputters, engine dies.
2. She starts up, I rev the engine, engine sputters, engine dies.
3. She starts up, engine idles, I rev the engine, engine runs fine, I throw the car in drive/reverse, engine sputters, I rev the engine, engine runs, I drive off(up hill), engine dies. (I actually don't know if the hill makes a diffrence but I haven't been able to test it on a downward slope)
4. Car starts up fine, I warm up the engine, I drive off, but the first few minutes of the drive (after a 5minute warm-up) the engine almost dies, but will usually come back with a few revs. I live near a highway so for the first mile or so getting from zero to 55 is like new driver figuring out manual transmission, she runs, she stals, she runs, she stalls. After the first mile or so the problem stops and the drive is smooth.

In all cases, once the car actually starts and has been on the road for a couple of minutes I can shut her off, leave her idle, go through stop and go traffic, you name it, it's reliable and runs good.

So, now, how do I start it...

After getting pissed off the car won't start. I pop the hood open, take off the air filter, grab the nearest can of gas, and pour a few ounces directly into the carberator. Try starting the car again, wash rinse repeat 3-4 times. After about 3 tries I get a good rev, the engine usually backfires, I get some white smoke out of the tail pipe and it'll stall and die again. At this point I add one last treatment of fule to the carb and she starts up, the engine goes from a slow idle to a fairly fast one. I let it sit at the higher idle for 30sec or so, tap the gas peddle and the engine resets to it's slower idle speed. At this point the car is good to drive until I leave it off for more then 24hours.

I don't have extensive experience mechanically, my background is in electronics, but when I'm troubleshooting the intermitent ones are the hardest to figure out. Since I have no reliable way of replicating the issue other then just letting the car sit for more then a day I'm kind of stumped as to how to go about figure out what's wrong with it. Since it does start and it does run well I would assume all the parts are functioning properly. Having to add fuel into the carb and the fact that the engine dies/sputters when I press the gas peddle I would assume it's a fuel issue and more then likely I just need to replace the fuel pump?

Anyway, I was hoping someone has heard/seen this problem before and it might just be a simple adjustment.

Thanks for the help

I would check the choke first. Sounds like it is not closing and then not controling the idle with the engine cold.

sounds like the choke to me too,

A dirty fuel filter can cause a lot of problems. It's cheap and easy, and if it doesn't fix your problem it's probably a good idea to do anyways. Dirty fuel filters do cause the fuel pump to work a lot harder causing them to fail, so it is possible your fuel pump is about to go out. Unfortunately the fuel pump is going to be quite a bit harder to replace if you don't have much mechanical experience. I would personally start with the fuel filter first, then go from there. Good luck.

A carburator is a whole lot different from the EFI that you are likely used to -- you tune it for warmed-up driving at the expense of cold start performance -- the choke helps, but it can only do so much -- the PCM that controls EFI modifies just about everything posible to make a cold start smooth, and the transition to warmup occur faster -- this starts with a high temp (think 195 deg. F) thermostat -- it also does choke and fast idle function (running rich and idling higher when cold) -- additionally, the timing is adjusted (advanced) to help the engine stay running until the coolant temp increaes enough for the engine to run with O2 sensor feedback -- a carb cannot do all of this, especially if it only has engine vacuum to rely on.

If you smell gas while the engine is stalling out, the choke may be stuck closed or not opening completely, but it could also be the carb itself -- old Rochester's can leak fuel through the throttle shaft (this is usually how they die) -- a cold engine cannot burn excess fuel every easily, so it will just flood and die until the fuel can evaporate, or get drawn through by dry cranking. Adding more fuel directly into the carb or using starting fluid may not help in this case.

When the last time you did a tune up?

I'll bet on the choke not working at all, it is stuck open. Things to look for are: Sticky choke linkage, a little Gumout spray is good for that. Not knowing what carb you have (2GC, 2GV) you can have a couple of choke spring options. Most likely you have the thermostatic spring (in the housing on the passenger side of the carb) that opens the choke as the car warms up. There might be another coil spring right under it on the manifold, this allows the choke to close by operating the choke rod.

Do a Google search and you should be able to find out anything you need to know. It may be a case of an adjustment only, or a choke rod has possibly popped off.

When the car is dead cold, press the gas pedal to the floor once, get out of the car and look at the choke. The choke plate should be almost totally closed. If not, you'll have to find out why this is not happening.

I think it is something between the choke rod spring on the manifold and the basic choke adjustment.

Bob