Hello all, like the title says. It would appear my car is slightly flooding when shut off when engine is warm or while driving at very low rpm. I’m running a holly street avenger and have followed the tuning guides and such. Everything seems to run great otherwise, just wanted to try and fine tune this minor issue.

thanks I’m advance!

 

What is the fuel system?

 

Sorry, Holley street avenger 670 carb, with Mech fuel pump. 350

 

About 6 psi fuel pressure

 

I dropped it down to about 5psi to see if it makes a difference.

 

A slightly leaking needle & seat ?

 

thanks for the reply. How would one check to see if the needle and seat are leaking?

 

When I remove the screws on the side of the float to adjust the fuel level, the fuel is just below while running. Would that say the the needle and seats are good? How long should the fuel pressure stay without moving after shutting off the car? As I have a gauge installed after the regulator.

 

Hi caddyescalade, sorry it took a while to get back to you, I had a pretty busy week compounded by a computer malfunction.

That would indicate that the float level is set properly, What you really want to see is if that level rises any immediately after shutting the engine off. A slight needle & seat leak might not show up while running above idle speed because the engine would be burning any slight amount of extra fuel but when shut off it would collect in the manifold with no running engine to suck it in and burn it off. All things being equal I'd expect it to hold pressure when shut off for at least long enough to check the level by removing the float bowl screws that you mention . Have you tried running it, shut it off, and then look down the carb throat to see if fuel is percolating into the manifold?

 

Awesome, thanks for the help. I’ll check it out and post back.

 

Thought I’d report back, the floats don’t appear to rise after shutting the car off and I don’t see any evidence of fuel going down through. So does that mean my needle and seat are fine? Is this something I should just replace anyway?

 

I wouldn't replace anything till the cause is determined. When I was mentioning to "see if it rises" I was talking about the fuel level itself and not the floats. I guess the bottom line is that if you can't see fuel leaking down into the manifold after you shut it off are you sure it actually is flooding? Are you smelling excessive raw fuel from the exhaust?

 

Can definitely smell the fuel from exhaust. I’ve since noticed that if I let the car idle for a while it slowly builds up fuel to the point the engine misses or chugs when hitting the gas again until the excess is burned up. So it would appear at idle and very low rpm there is slightly too much gas going in. What adjustment would that be?

thanks again

 

So I gotta ask, have you attempted to adjust the idle mixture screws? The screw with the pen pointing to it in my picture is one of the two screws that adjust the idle fuel mixture (there is also one exactly opposite of it on the other side of the carb, don't touch the pair on the back of the carb, those are for when the secondarys open only, when your punching the gas pedal in other words, and aren't involved in your idle) . If you've followed Holley's instructions for adjusting those screws and it still runs too rich at idle, you may have deeper carb troubles than can be easily diagnosed on line.

 

I'm very familiar with the Street Avenger carb. Have you checked the float level on both primary and secondary sides?
Does the problem occur only when the engine is hot? ...