Weber idf 44 leak!, Help! Options

[72hardtop]

What type if any fuel pressure regulator are you using. Pressure is paramount no more than 3.5lbs. Also very carefully check the carb top gasket and make sure none of the ports are blocked or partially blocked.

[Milkman7286]

You installed the spacers too?

This fuel you see on top of the butterfly, can you tell us where it's coming from? The pump jets, the aux vent or from some other location?

We really need pictures to help you.

When you open the butterfly, even slightly, you actuate the accelerator pump. That squirts fuel from the pump jets. There will be one on each throat of the carb.

It appears to be coming from the progression/transition ports.

[Milkman7286]

What type if any fuel pressure regulator are you using. Pressure is paramount no more than 3.5lbs. Also very carefully check the carb top gasket and make sure none of the ports are blocked or partially blocked.

I'm using a Holley regulator with a seperate gauge. I have it set at 2.5 now confirmed by the gauge. I just put new gaskets on and it still does it. I have checked that the ports are not blocked. It did it with the old gasket and with the new

[jmill]

Theres only a couple of reasons to have fuel leaking out of the progression ports with the engine off.

1- idle jet air vent blocked and you're siphoning fuel from the fuel well.

2 - heated soaked and its boiling up and out.

3- flawed casting. (Seriously doubt it)

Check the vent really well and ensure its clear. Did you install the spacers?

[stugray]

Check the vent really well and ensure its clear.

That is what I meant earlier.
It sounds like you are pressurizing the bowl.

Any chance you are using a really powerful pump?
I have heard of fuel pumps cavitating and blowing bubbles into the fuel.

This was happening with some of the guys at the track that run E85 & megasquirts.
They couldnt figure out what was happening until they put in a clear fuel line.
That was with a high pressure FP and FI, but still a thought.

[jmill]

The float bowl vent (which is a huge slotted hole) and the idle jet vent are two different things.

Idle jet vent is kinda like the AC jet for the idle jet. Air sucked in there mixes with fuel from idle jet and gives you your idle mixture.

[Milkman7286]

The float bowl vent (which is a huge slotted hole) and the idle jet vent are two different things.

Idle jet vent is kinda like the AC jet for the idle jet. Air sucked in there mixes with fuel from idle jet and gives you your idle mixture.

I haven't checked the float bowl vent just yet. That being said, the carb leaked from the mixture screw hole with the gasket and float completely off the carb so.

What keeps the fuel from dripping on its own on these carbs? I mean the mixture screw is at the bottom of the carb and the progression ports are fairly low too. Since gas is above these points what stops fuel from leaking just by way of gravity?

[Milkman7286]

Check the vent really well and ensure its clear.

That is what I meant earlier.
It sounds like you are pressurizing the bowl.

Any chance you are using a really powerful pump?
I have heard of fuel pumps cavitating and blowing bubbles into the fuel.

This was happening with some of the guys at the track that run E85 & megasquirts.
They couldnt figure out what was happening until they put in a clear fuel line.
That was with a high pressure FP and FI, but still a thought.

Before I bought the regulator my gauge was reading 4 psi so I don't think that would be the issue. I wish the fix was just too much fuel pressure (IMG:style_emoticons/default/sad.gif)

[Milkman7286]

Theres only a couple of reasons to have fuel leaking out of the progression ports with the engine off.

1- idle jet air vent blocked and you're siphoning fuel from the fuel well.

2 - heated soaked and its boiling up and out.

3- flawed casting. (Seriously doubt it)

Check the vent really well and ensure its clear. Did you install the spacers?

I did install the spacers. However the motor wasn't even remotely warm and it still did it. I let the car idle for maybe 60 seconds.

What is the best way to clean those idle jet air vents? I have blown through with carb cleaner and air and when I do I can see it spraying into the float bowl and if I remember correctly it comes out of the progression ports as well. Is anyone sticking safety pins or anything in there to really make sure it is clean and there isn't a hard piece of debris or something like that in there?

[jmill]

What keeps the fuel from dripping on its own on these carbs? I mean the mixture screw is at the bottom of the carb and the progression ports are fairly low too. Since gas is above these points what stops fuel from leaking just by way of gravity?

The idle circuit takes its fuel from the main fuel well. It then loops up higher than the float level and then comes back down to the progression ports and mixture screw. The idle air jet is at the top of the loop which breaks the siphon and stops the flow. A plugged idle air jet won't break the siphon and fuel will continue to flow until the float bowl is empty. Your idle mixture will also be super rich.

To clean it, remove the idle jet on the offending cylinder and blow from the vent (idle air jet) down. You'll easily see when it's clean. If there's crud, make sure to get it out so it doesn't plug up the idle circuit. You can stick something in there as long as it doesn't booger up the hole. Get that whole circuit super clean.

[Milkman7286]

What keeps the fuel from dripping on its own on these carbs? I mean the mixture screw is at the bottom of the carb and the progression ports are fairly low too. Since gas is above these points what stops fuel from leaking just by way of gravity?

The idle circuit takes its fuel from the main fuel well. It then loops up higher than the float level and then comes back down to the progression ports and mixture screw. The idle air jet is at the top of the loop which breaks the siphon and stops the flow. A plugged idle air jet won't break the siphon and fuel will continue to flow until the float bowl is empty. Your idle mixture will also be super rich.

To clean it, remove the idle jet on the offending cylinder and blow from the vent (idle air jet) down. You'll easily see when it's clean. If there's crud, make sure to get it out so it doesn't plug up the idle circuit. You can stick something in there as long as it doesn't booger up the hole. Get that whole circuit super clean.

Thanks for the breakdown. That is super helpful to me because I am a very visual person and since I can't see what is going on inside the carbs I can't understand it exactly. I'm assuming that vacuum pulls the fuel through this system when operating correctly?

You know, I actually have done the above a few times and when I do it sprays carb cleaner through the idle circuit very cleanly and with good pressure so I'll have to step it up and stick something through the hole. Any ideas what to use? I asse I need something strong but thin.

[rhodyguy]

when the engine is running does the engine respond at all when you adjust the idle air mixture screw on the bad venturi? don't stick ANYTHING into the passageways/ports, i.e. a paperclip or wire. when clearing out a jet blow the air opposite to the flow of fuel.

[stugray]

This is somewhat related since it sounds like the OP has had the top of his carbs on & off numerous times.

Anyone know where to get the weber IDF carb top gasket by itself?

I would like to have a couple spares but dont want to pay $30 each for the complete rebuild kits.

[Milkman7286]

when the engine is running does the engine respond at all when you adjust the idle air mixture screw on the bad venturi? don't stick ANYTHING into the passageways/ports, i.e. a paperclip or wire. when clearing out a jet blow the air opposite to the flow of fuel.

Yes, the mixture screw does respond on that cylinder. I wondered that too earlier in this whole thing lol.

I'll keep trying to blow air and cleaned through that vent hole I suppose :/

[jmill]

Don't stick ANYTHING into the passageways/ports, i.e. a paperclip or wire. when clearing out a jet blow the air opposite to the flow of fuel.

I completely agree it's bad practice. Unfortunately, it's next to impossible to blow air back on the idle air jet. Can't see how you can get an air chuck inside the idle jet hole to blow back up air jet. It's easier to blow air down from top and catch debris inside idle jet hole. If your not ham fisted you can mechanically remove crud without marring the air jet or plugging the short passage.

[Milkman7286]

Don't stick ANYTHING into the passageways/ports, i.e. a paperclip or wire. when clearing out a jet blow the air opposite to the flow of fuel.

I completely agree it's bad practice. Unfortunately, it's next to impossible to blow air back on the idle air jet. Can't see how you can get an air chuck inside the idle jet hole to blow back up air jet. It's easier to blow air down from top and catch debris inside idle jet hole. If your not ham fisted you can mechanically remove crud without marring the air jet or plugging the short passage.

I'll see what I can do. I'm still not sold on this being the issue. I have blown through it a good number of times and it will blow carb cleaner through to the float bowl with pretty good force.

[jmill]

There's 3 holes that need to be clear. I made a quick drawing of the idle circuit for you. It's the top air jet you need to make sure isn't blocked.

If it's not that, I'm out of ideas.

[Milkman7286]

Update:
Last night I put in a new seat and needle just in case. I also cleaned the idle air bleed and it is so clean you could eat in there now.

No change.

However, I did confirm my theory about the throttle plate. Last night after completing the above the carb started to gurgle again. As it was doing so, I grabbed the non-linkage side of the throttle arm (thing that the throttle plates sit on, no idea what the correct term is) and with a tiny amount of pushing I closed it just a little bit further. Gurgling stopped. Then I let go and the gurgling began again. I immediately pushed it again to see if the gurgling would stop and sure enough it did.
So the throttle plate isn't correctly positioned or closing all the way? Not sure.

I also have one more thing to add. Last I checked, the mixture screw responded to adjustments. I'm about 90% sure it was responding last week. Last night I tried playing with it and it is in fact NOT responding to adjustments. Normally I would assume this is a vacuum leak so I sprayed carb cleaner all over the place but was unable to get the engine to stumble.

[ThePaintedMan]

You mentioned in your original post that you "adjusted" the butterflies on one of the carbs. I think at this point you need to check to see that they're closing all the way. Most likely the plate isn't aligned correctly in the bore. At worst case you have a bent/twisted throttle shaft. Take the carb off again, remove the top and the chokes, then place a flashlight in the bores in a dark room. You'll be able to assess how the plates are aligned and note any major passage of light past the plate.

If the throttle plate does not close all the way and in harmony with the one next to it, you will not get much, if any adjustment from the mixture screw as too much air is flowing past the throttle plate for the idle circuit to function.

[Milkman7286]

You mentioned in your original post that you "adjusted" the butterflies on one of the carbs. I think at this point you need to check to see that they're closing all the way. Most likely the plate isn't aligned correctly in the bore. At worst case you have a bent/twisted throttle shaft. Take the carb off again, remove the top and the chokes, then place a flashlight in the bores in a dark room. You'll be able to assess how the plates are aligned and note any major passage of light past the plate.

If the throttle plate does not close all the way and in harmony with the one next to it, you will not get much, if any adjustment from the mixture screw as too much air is flowing past the throttle plate for the idle circuit to function.

I will readjust the throttle plate when I get home and I'll take a look at how it sits in relation to the lowest progression hole. What I'm now wondering is: if the lowest progression hole is open and exposed below the throttle plate, would fuel leak out (with engine off) because the throttle plate isn't covering it?