Holley carb problem Just started happening

[toofun]

So I have a mechanical secondary Holley carb that has been working FLAWLESSLY on my car. It tended to leak fuel ever so slightly but nothing major. It would always start right up and idle right away happily at around 1000rpm. Blip the throttle and it would have no hesitation at all and very very responsive.

I noticed the other day a very strong gas smell in the garage. Pulled the car out and started it up. It ran very very rough and when I tried to get it to idle it would idle then chug down slowly until it would finally die (not right away but about 15 seconds later) When I shut the car off I could see fuel on top of the intake. So I cleaned all of it off removed the air cleaner and started the car.. NO LEAKS but it still would run rough and I had to hit the throttle to keep it running. When I hit the throttle it would be very very responsive with NO HESITATION at all. I tried adjusting the idle but all that did was make the engine idle HIGHER once I hit the throttle and then over 30 seconds later it would go from 1500 rpms to 1000 rpms and chug at 500 rpms.

Couple of notes.. the car runs an electric fuel pump and it reads steady at 8 lbs. It is deadheaded at the carb dual feed with a return line. Again this car ran flawlessly for about two months and 5000 miles with this setup. It just seems like all of a sudden this happened. I also checked all the vaccuum lines and plugs to be sure none came off. Any help would be greatly appreciated. Could it be the idle circuit? What should I check first? Not very carb savvy so any help is appreciated.

Thanks in advance

Mark
TOOFUN

[Thephranc]

I'd check float levels first.

[Quickboat]

My first guess would be fuel. There is some real crap fuel out there. Did you fill it up just before putting it away? Could be as simple as water in the gas. this wreaks havoc on idle mixtures since water lays at the bottom of the bowls. Pull the bowls and blow everything out before major adjustments are made.

[mincharlie]

Could be garbage in the fuel! Causing problems for the needle and seat. This would cause flooding and a bad idle. Make sure that the floats are not sticking due to this. Also if this is happening make sure all that fuel is not geting into the oil.

[Red67Mustang]

Float levels. Consider replacing the needle & seat valve to make sure float levels are maintained at the correct level.

[toofun]

I did notice one more thing... after the car is shut off I can hear fuel going into the carb. I would say about a teaspoon is trickling into the carb..... and after further reading on the net I found a great article that explains the problem I am having with the carb. Especially the part that says that fuel is leaking past the needle and float and dripping onto the throttle plates after shutdown... I am going to pull the bowls, needle and seats and take a good look at everything as well as adjust the pressure on the regulator to 6 psi from the 8 I am running. Anyways I will report back once I take a look... Here is the link that shows a great description as well as pics of how to remove it step by step as well as setting it back up for baseline adjustments...

http://www.vintagemusclecarparts.com/pages/needleandseat1.html

Mark
TOOFUN

[mincharlie]

Make sure your oil is not contaminated with the fuel that was pouring into the intake after shut down. Some fuel will get by the rings if it sits on top of the pistons after shut down.

[toofun]

Well I checked the float level and yup it was too high. Pulled the needle and seat which looked really good but gave it all a real good shot of carb cleaner, readjusted the float and BAM! Started right up and sat at a perfect 850 idle with super response. Only thing is the needle and seat are at the very end of their adjustment. I just barely got the nut back on to retighten everything back up. But it runs PERFECT like it did before. If it happens again I can only assume that maybe the float may have a hole in it and it is not comeing all the way up??? Is that why there is not any adjustment left on the float? I also lowered the fuel pressure to 5.5 lbs of pressure as well. KEEPING MY FINGERS CROSSED BUT ALL IS GOOD!

Now I will change out the oil and filter just for a good bit of insurance just in case some fuel got mixed in...

Mark
TOOFUN

[mincharlie]

That's good news! When the float is to high or there is dirt between the needle and seat the fuel will just keep coming into the bowl. Then drain into the carb which will cause these systems. Did you find any dirt in the bowls? If so make sure you have a filter between the pump and carb. Your floats should be fine and lowering the fuel pressure was a good idea.

Dan

[Thephranc]

The floats where they hinge at can bend over time. You may want to get new floats and then readjust the needle and seat.