I've been having some trouble with my 1981 Pontiac Parisienne lately and I'm pretty stumped. It's got a 305 with a 4bbl electric choke Quadrajet. She starts up like a dream every time as long as she's cold or hot. There seems to be a grey area between cold and hot that's causing problems. Generally I drive the car to and from work and it sits for a minimum of 8 hours in between trips. From a cold start i have only to hold my foot ever-so-slightly on the gas while turning the key and she starts up instantly. If I stop anywhere else it's usually for no more than 15 minutes and it starts up fine without touching the gas. My issues start when the car has been sitting between 30 minutes and 3 hours. In that situation, whether I give it any gas during startup or not it acts like it's flooded. It won't turn over unless I put the gas to the floor and hold it there until it starts, belching black smoke that smells almost like diesel from the tailpipe. Tonight after sitting for two hours it started but coughed and sputtered for about 30 secs before dying. Once I put my foot to the floor I was able to get it started but the whole parking lot reeked of gas as I hastily got the he'll out of there. I put in a new set of plugs and wires a couple of months ago, followed by a rebuilt carb and a new hot air door valve and a heat riser vacuum valve. The carb has it running a fair bit less rich but I still seem to be having these starting issues. I can swap out pretty much anything, it's diagnostic experience that I lack. Has anyone got any ideas where I should start looking?
My guess is the primary fuel bowl is leaking or possibly the needle and seat assembly is not sealing. Could be leaking fuel into the intake. The leak might not be bad enough to cause issues when sitting for 15 minutes or less, but will when sitting more than 15 minutes. Curious that it clears up after 3 hours though. Next time you have the opportunity after it has been sitting and won't start I would pull the plugs and see if they are fouled. Who did the rebuild? Just because it was rebuilt doesn't mean it was done right. Most aftermarket rebuild jobs are not the best. A while ago I found an article outlining a bunch of different Q-Jet issues and symptoms. I'll see if I can find it.
I pulled the factory carb off and replaced it with a rebuilt from National. I figured that was the safest way to get a decent one.
Have a look at this. There's a lot of info, but it's pretty good info. http://www.florida4x4.com/tech/quadrajet/qjtshoot.pdf
Rebuilt carb has been top notch, apart from this little oddity. I was a little concerned when it arrived as it was a little bit different than the stock carb. A little bit of fiddling had it running just fine.
That's a lot of reading! I'll dive into that and see where that lands me. After some unseasonably warm weather it suddenly got a little cold out to work under then hood so this may wait for warmer days.
Some members brag about fuel injection and all that fancy electronic stuff. But ya can't beat a carburator you can fiddle with and drive.
As a hard-core computer geek; in my case a little fiddling means blind fumbling. I was stunned that I got it to run again at all.
Maybe a car-guy friend can re-adjust it even better. Amazing what a little carburator fiddling can do when they know how to tune one. Gone are the days when you could gas up and tell Joe, the pump jockey, your engine isn't runing right and he would fix it as the 29 cent gas was being pumped.
All my car-guy friends are right here on the forum. My mechanic has griped at me several times for repeatedly bringing in a car that's older than all of his staff. He has to come out from behind the counter and work on my car himself. He did a pretty good job of tuning it despite his grumbling.
Real car guys are that way! He did a pretty good job of tuning it despite his grumbling. Haven't you noticed that from here?
