fuel dumping in carb?

[1BAD68]

I have trouble with hot starts, acts like its flooded.
Yesterday I noticed that when engine is hot after I shut it off, fuel is going down the carb, looks like a coffemaker just perculating.
I figured it was the floats or float seats so I ripped it all apart and cleaned it nicely but floats and seats were fine. Put it back together and fired it up, got it hot and shut it off and fuel is still bubbling down the carb.
I also noticed that my clear fuel filter was half full of gas and air was bubbling through it for about 3 minutes or so.
Why is this happening?

[Joshua]

What carb/intake??
Sounds like the carb is getting hot to the point of boiling the fuel, the fuel will then "burble" high enough to spill from vent.....I've had similar problems....added a 1/2" Phelonic spacer under the carb.
It's much better, but will sometime still act up on really hot days after shutting off.....it'll start back up fine after sitting for a bit, but not right afterwords......giving a bit of throttle to let in more air to compenstae for the extra fuel that dribbled in helps.....my car would also stumble shortly after it got started, say pulling out in the road and stepping on it for example.......

[1BAD68]

its a Edelbrock 600 on a Performer intake, would "boiling' gas in the carb be noticeable in the in-line filter? its about 10" away from carb.

[Joshua]

Engine mounted fuel pump? Steel lines from it?
Yes, I think you would see it there as well......depending on where the filter is mounted..... Above the exhaust manifolds? Does it "lay" on the intake?
There are a few different factors that could all be contributing to the problem.......

[1BAD68]

Engine mounted fuel pump? Steel lines from it?
Above the exhaust manifolds? Does it "lay" on the intake?

all of the above.

[histoy]

On another site I read that years ago when cars had carbs, the gasoline was formulated in a way that would help prevent hot engine perculation, but that is no longer done with today's higher pressure fuel systems. 

[firefighter3931]

On another site I read that years ago when cars had carbs, the gasoline was formulated in a way that would help prevent hot engine perculation, but that is no longer done with today's higher pressure fuel systems. 

I've posted that here several times in the last few years. Basicly the vapor point of todays fuel is lower and less tolerant of heat due to the reformulation for fuel injection....which creates heat related issues for carburated engines. The best thing to do is to keep the fuel as cool as possible by isolating the fuel lines from heat sources and insulating the carb with a spacer or insulating base gasket. It also helps to block off the heat crossover, especially when using an aluminum intake manifold....aluminum conducts heat much better than cast iron. 



Ron

[1BAD68]

I found out that I installed my fuel filter backwards last time I cleaned it, DOH!
Now it doesn't perculate down the carb but still bubbles in the filter.
It seems like when its running the filter is only half full of fuel, when I give it a shot with the throttle it fills the filter with fuel and then goes back to half full and starts bubbling.
Is it normal to have air in the fuel line when its running? I've never noticed that before.
The fuel line looks good all the way back to the tank, no leaks so I'm assuming its not sucking air.

[69chargeryeehaa]

install the insulator gasket, it will cure all your issues.  Your seeing the classic symptoms of vapor lock, the "bubbles" is fuel boiling in your carb because it's too hot.  If you can't hold your finger on the carb (meaning it's just warm) then you need the insulator gasket, chances are your intake is so hot you can't hold your finger on it for more than 1 sec without getting burnt.   

[1BAD68]

the carb is sitting on a brass spacer about a 1/8" thick sandwiched between two black gaskets. Do I need a different one?

[69chargeryeehaa]

yes, an insulator one: http://www.edelbrock.com/automotive_new/mc/carbs_acc/access_thun_perf.shtml

[1BAD68]

cool, thanks