Start Up Blues

[Hijinx]

Guys,
I am having an odd problem. In the last few weeks, when I first start up, after she has sat a few days, it blows black smoke and idles like its only firing on a few cylinders. I have to sit there and feather the throttle for a few minutes and then she levels out and runs fine.
Now here is my thought on this. I noticed a heavy raw gas smell near the carb. Noticed a small amount of fuel puddled on the passenger side intake. Seems to be leaking from the base of the carb. With that said, I am wondering if its leaking down on the inside and into some of the cylinders. This would explain the heavy black smoke.
What do you think? Remember, I have that new Speed Demon carb in place. So I have no idea why it would be leaking down. the fuel bowl levels are not high, about half way in the site glass.
I'm stumped.

 

[cmegga]

I dont have any advise for you, but just out of couriosity what has the temp been down there when this started??

I only ask becase Im seeing the same type of issuse and Im assuming my problem here in NY is due to the temp change. I get the same start when its 50 or below. Real hard to get it running then it like its barley firing for the fist 5- 10 minuets.

I do see some smoke as well, but I get white smoke and only for about the first 30 seconds or so.

On the warm days she starts much much better for me .. It does it a bit, but not nearly as bad.

I have to guess it just doesnt like the cold or my choke is not opperating correctly.

 

[cntrhub]

Hijinx, Please fix that fuel leak!!! Do you have a loose or poor fitting fuel line going on somewhere? Sounds like this car is going to catch fire eventually. Dry the puddle. Start the car, and look for that leak... NOW!!
Did the bolt(s) that secures the carb to the manifold, work loose from engine heat cycles? The fuel could be blowing out and puddling between the gasket and carb on the side you mentioned?
Upon cold start-up, are you touching the gas pedal? You might want to find the idiosyncrasy to this carb. Meaning....on cold starts, don't touch the gas pedal, just crank the engine. Did this start quicker? Punch the gas pedal once or twice, (squirt initial fuel from the accel pump) don't touch the pedal again. Did this start easier? Step on the gas pedal to the floor and don't let up. Now crank the engine over. Did the engine kick over, and light right up? You need to try these or other combinations to see what the engine responds to.
You are leaning (no pun intended) in the right direction about the black smoke. This is a rich condition. Black smoke = excess fuel. Blue smoke = burning oil. White smoke = vapor (condensation) or coolant leak.
Choke plates on for too long?

 

[DanC]

cntrhub has the right idea. Fix this before you have big problems.

It sounds like your carb is slowly draining fuel from the float bowl into and onto the engine. The fuel accumulating on the intake manifold may be what is weeping through the carb to intake manifold gasket or throttle shafts.

On older Quadrajets (70's vintage), a lead plug in the bottom of the fuel bowl would loosen over time and allow fuel to drain causing the kind of hard starts you describe. Not being familiar with the Demon, I don't know if that could be the case, just something to consider.

Hope this helps.
DanC

 

[Hijinx]

Thanks all. I am going to have to take it down to find out. I hate not driving it right now, the weather here (Dallas) is great! We get about a week of this kinda fall weather each year and I'm missing it!

I think its leaking between the carb and the spacer. May have a bad gasket. I'll let you know.

 

[Hijinx]

Well, just pulled the carb and there's tons of fuel puddled on the gasket under it! Brand new Demon and it's doin this! I'll be callin them in the morning.