# Weber Experts... Gather Around!



## WCHLVR (May 27, 2002)

I have an interesting situation and can find no reason for it! I have a 75 Bunny w/ VERY stock 1.5L and a Progressive Weber conversion (yes it is way over carbed but oh well). I have rebuild the carb twice and yet it still suffers from a flooding problem. If it is cold it will start with just a click of the switch (it starts better than my '05 Jeep Liberty.) After it has warmed up, shut the motor off, and let it sit for 10-15 mins. it floods out and you have to hold the throttle to the floor to get it started. It took me awhile to figure out where the flooding was coming from but I have NO idea WHY! It is slowly dripping fuel from the accelerator pump injector nozzle. Enough so that it will drain the pressure off the fuel system. Here is what I know...
-Carb is SUPER clean.
-The carb has been rebuilt twice (the most recent rebuilt was with a OEM Weber kit) this includes the needle and seat.
-I have replaced the float.
-All of the pumps have been replaced
-It has nothing to do with fuel pressure as I can pull the carb top and watch it drain the fuel bowl.
-It runs great once you get it started.
-My gas mileage has went through the toilet















The ports I am refering to are right behind here in the float bowl...








And it is leaking out of here...








I am at my wits end! Anyone have any ideas!
This...








Is in This...










_Modified by WCHLVR at 2:03 PM 1-17-2006_


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_You need to ask yourself what could happen to the carb from 15 minutes of sitting after the engine has be shut off.
*I know that is dripping fuel from the accelerator pump nozzle and flooding the intake manifold with raw fuel.*
If it is flooding, why would you need to hold the acc petal down to get it re-started?
*Because it is SOOOOO loaded with fuel it is the only way to get enough air in there to get it to fire off.*
Are you saying the fuel bowl is emptying itself after the engine is shut off?
*Yes! I can actually watch air bubbles rise from a port on the side of the float bowl. This port is right behind the accelerator pump.* 
Does it take about 5-10 seconds of cranking to get it going again?
*Yes! Because the is SOOOOO much raw fuel sitting in the manifold.*
From the pic that you posted, I couldn't see if you had a fuel return line to the tank? Do you have one?
*No! This is a '75 and it was never equipped with a return line.* You should either have a return outlet on the mechanical pump, or a return outlet from your fuel filter.
*Either of these are equipped to have a return line and the tank does not have a port for this either. I have never had to have return line on a carb setup before... why would I need one now?*
And, one more question: where is the vacuum line on the canister on the distributor hooked to on the other end?
*It is connected to the base of the carb. Right next to the Air mixture adjustment screw.*



_Modified by WCHLVR at 9:40 AM 1-17-2006_


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_Ok. I am understanding better.
What is the fuel pressure going into the carburetor? Fuel pressure should not exceed 3.5 psi for that carburetor. I don't see a fuel pressure regulator on there.
*I am not sure. It has a OEM mechanical fuel pump that is bolted to the front of the motor. But I can pull the fuel line and the top of the carb and watch the fuel siphon out of the bowl.*
I am just wondering if your fuel pressure is too high going into the carburetor, and if the float valve is not able to shut off the gas coming in.
*It is NOT over-flowing the bowl. It is draining the float bowl.*
It is a separate issue, but check you vac canister to make sure it is tight. Pull the hose off the carb and suck on it to see if it tightens up. A leaking canister can cost you dearly in tuning problems and fuel economy.
*I don't think there is an issue with the Vac Ad canister because when it is running is runs like a bat out of hell and infact it pulls harder than my buddies 1.8L. I will run that test when I get home.*
I assumed all the carb setups had return lines. Guess that was a premature assumption. Where does your fuel line come out of the tank? Out of the sender? If so, you are telling me there is only one fuel nipple on top of the sender?
*The '75s (and early '76s) have the sender on the side of the tank and the single fuel fitting is near the very bottom of the tank.*

_Modified by chickenfriend at 12:56 PM 1-17-2006_


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## machschnelGTI (Jun 28, 2004)

*Re: Weber Experts... Gather Around! (WCHLVR)*

If its draining the bowl, then there is a crack in the bottom of the bowl or something is loose. Any fuel that goes through the jets at the bottom of the bowl has to go up to the venturi level before it can get into the barrels, so that can't be draining your fuel. Check the idle circuit aswell, those jets exit very low in the barrels, make sure all the jets are tight.


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (machschnelGTI)*


_Quote, originally posted by *machschnelGTI* »_If its draining the bowl, then there is a crack in the bottom of the bowl or something is loose. Any fuel that goes through the jets at the bottom of the bowl has to go up to the venturi level before it can get into the barrels, so that can't be draining your fuel. Check the idle circuit aswell, those jets exit very low in the barrels, make sure all the jets are tight.

It is *NOT* leaking through the bowl. It is *NOT* draining through the jets at the bottom of the bowl. There are *NO* cracks. Oh and believe me *EVERYTHING* is tight. It is some how siphoning fuel *UP* to the accelerator pump nozzle and dripping out there. The nozzle is at the top of the carb. There are two ports to the side of the float bowl that supply fuel to the accelerator pump. It is pulling the fuel through there, pulling it up to the nozzle and dripping into the carb.


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (WCHLVR)*

Bump for edit! Added pics of the areas of concern!


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_Isn't the accelerator outlet above the level of the fuel in the fuel bowel? 
*YES!*
And if it is, how could *all* the fuel be "siphoning" out of the accelerator jet?
*Now not all the fuel is emptied but a fair mount is and all the fuel pressure is relieved.*

That would be an impossibility if everything is at atmospheric pressure.
*Using the concept of siphoning gas from a tank you create a vacuum, my question is where is the vacuum coming from? I have removed the accelerator pump nozzle and watched the fuel spill over.*
_Modified by chickenfriend at 6:46 PM 1-17-2006_


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## antichristonwheels (Jun 14, 2001)

*Re: Weber Experts... Gather Around! (WCHLVR)*

Has the car been in freezing weather? It's possible some small amount of water in it froze and busted something you cannot see. Just because the carb looks good doesn't mean it is.


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## efreeman (Jan 16, 2004)

*Re: Weber Experts... Gather Around! (antichristonwheels)*

I have one of these Webers sitting in my storage garage that is virtually brand new. Installed it back in '90 when I needed to smog my (then) CA '75 and had to remove the twin DCOE's on her. Now, I'm in PNW and can run the sidedrafts with no hassles. I'll take a look at the carb this weekend to see what could be causing the problem. I know on some of the old Holleys and such that I worked on that there was a small ball and spring on the accelerator pump circuit that kept the outlet from the pump closed until enough pressure built up and then popped open allowing fuel to pass by. If your Weber has something like that and it went missing on the first rebuild, it could be the cause. I'd have to look at an exploded diagram to see just what is in that pump circuit. Will check online tonight to see what's out there.
Eric


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (antichristonwheels)*


_Quote, originally posted by *antichristonwheels* »_Has the car been in freezing weather? It's possible some small amount of water in it froze and busted something you cannot see. Just because the carb looks good doesn't mean it is.

No freezing weather


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_I have been thinking about this a little more. You mentioned that you replaced the float. Had the float sprung a leak?
*No I just swapped it to see if that was the problem.*
Are you sure the fuel bowl needle valve is working correctly? I am more inclined now to believe that this could be the problem. Consider this scenario:
Fuel bowl needle valve not functioning, causing the fuel to overflow the bowl and pressurize the inside of the carburetor. Fuel then pushes its way through one way check valve into the accelerator circuit and abnormally pressurizing the circuit ( i could be wrong about this pressurization idea







). Fuel cannot bleed back to the bowl through the accelerator-to-bowl bleed jet, since the bowl is pressurized! Gas trapped in the accelerator circuit and the other circuits has no place to go but out the jets into the throat, the leakage of the accelerator jet being the most conspicuous leak and lasting longer than the other leaks.
Engine is cut-off, and fuel continues to flow out the accelerator jet *and the other jets* until the pressure in the bowl is relieved. Fuel possibly continues to flow out of the accelerator jet even though it has stopped flowing from the other jets, because the ball valve in the accelerator circuit closed once the bowl pressure went below the pressure in the accelerator circuit and maintained residual pressure longer. The diaphragm helps the storage of the gas under pressure.
Fuel stops flowing out the accelerator jet when the pressure is equalized in the accelerator pump circuit due to gas leaving the accelerator jet and gas that is _finally_ able to return to the bowl through the accelerator-to-bowl bleed jet.
I'd check your needle valve on the float and make sure it is cutting off the gas. 
*I can remove the carb top w/ the float and needle and seat and it still does it. There is not bowl pressure. When the fuel trickles out the nozzle air bubbles rise out of the port I was attempting to point out earlier and slowly reduces the amount of fuel in the bowl.*
Once you have the problem solved, I suggest checking your fuel pressure into the carb. I would guess your mechanical pump is putting out around 5 or 6 psi, which was ok for the oe carb, but is too much for the Weber.

Here is a diagram that likely resembles your carburetor, showing the accelerator circuit:








Number 44 is the check valve ball and 46 is the accelerator circuit-to-bowl bleed back jet. 41 is were you are seeing gas ushering forth.
j

_Modified by chickenfriend at 11:45 PM 1-17-2006_


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (efreeman)*


_Quote, originally posted by *efreeman* »_a small ball and spring on the accelerator pump circuit that kept the outlet from the pump closed until enough pressure built up and then popped open allowing fuel to pass by. If your Weber has something like that and it went missing on the first rebuild, it could be the cause. I'd have to look at an exploded diagram to see just what is in that pump circuit. Will check online tonight to see what's out there.
Eric

This is funny you should point this out. There was a check ball in the first kit I got (not Weber) and there was not one in the second kit (OEM Weber). All the diagrams I have seen for this carb do not show a check ball. I dropped it back in last night and it did not seem to make a difference (there is not spring). However I came home this evening from work and now then is no flooding and there is still fuel pressure in the line.







Now I wonder if there was suppose to be a spring too!


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## evilcaddie (Oct 23, 2003)

god i love that car


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## WCHLVR (May 27, 2002)

*Re: Weber Experts... Gather Around! (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_You said bubbles were coming into the accelerator circuit through a port. How does this air get in?

*shrugs sholders*


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## WCHLVR (May 27, 2002)

*Re: (evilcaddie)*


_Quote, originally posted by *evilcaddie* »_god i love that car

Thanks! It's a love hate relationship on this end!


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## WCHLVR (May 27, 2002)

*Re: (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_OK. My







last try...
If the fuel level is above the normal level in the bowl, is the level of the fuel above the outlet of the accelerator pump outlet jet?
*Nope! In fact the last time I got it apart the fuel level was WAY be low where it needed to be (because of the drainage) and it still was leaking*
If so, then that might explain the partial siphoning of fuel; the siphoning would continue until the bowl level has come down to the level of the jet outlet.
Level of fuel in the bowl is set by the float adjustment. You said in a post in the mk 1 section that the float level is set exactly, *but if the needle valve is leaking and/or the fuel pressure is too high, the fuel level in the bowl will be too high regardless.*

_Modified by chickenfriend at 2:04 AM 1-18-2006_


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## WCHLVR (May 27, 2002)

*Re: (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_Quote "*Nope! In fact the last time I got it apart the fuel level was WAY be low where it needed to be (because of the drainage) and it still was leaking*"
This does not make sense: How do you know where the fuel level is while the carburetor is operating, when it is leaking out before you get the carburetor open?
*It doesn't drain that fast. I drove the car around to warm it up. Pulled it in the garage and popped the top of the carb. It takes less the 2 mins to pull it.*
You didn't say anything about whether you replaced the bowl needle valve or checked it.
*Yes I did in the original post. In fact it has been replaced twice.*
You have said that gas is siphoning out the accelerator circuit, when the accelerator jet is above the level of gas in the bowl. I'll repeat myself: That is impossible. Siphoning works because of atmospheric pressure differential. Water does not run uphill.








*I share in your confusion however I stood there witha flashlight watching it do it. I should just take a video of it.*
But if the fuel is under pressure, that is something else.
Now let's talk about something we haven't discussed yet, shall we? 
You have said that air is issuing from one of the ports of the accelerator pump circuit leading into the bowl. Air should not be in the accelerator pump circuit!
*I argee fully*
How is the air getting in? Something is not tight=air is getting into the carb where is should not, like there is a piece missing, the pump cover gasket is bad or not sealing, pinhole in the carburetor housing, defective accelerator pump gasket. 
*I have replaced the pump twice and even replace the pump housing.*
If air is getting in it *might* be causing the gas to be pressurized and "boiled out", similar to what happens when fuel lines are too close to the engine heat (vapor lock). The accelerator pump area does get alot of heat from the exhaust manifold below, and if you do not have the 7mm heat insulator gasket between the carburetor and the intake manifold, the problem could be magnified.
*I was thinking about the insulator gasket as well but I thought it weird that it do need it now when it never needed it before.*
I suggest you take another look at the acc pump circuit and find out from Weber what all the parts that are supposed to be there are there. 
*I have review this several times. Nothing is missing and in fact there really isn't much to be missing. The kit that was NOT Weber showed a check ball however the kit from Weber and all the diagrams from Weber DO NOT show anything like that.*
You could call the place you got the rebuild kit and quiz them. Perhaps it is a defect in the carburetor housing--that happens sometimes with die cast items, and you might not be able to see the crack with the naked eye.
It might be a problem you will continue to overlook, and so if you depend on the car alot, it might be worthwhile to have the carb set to a professional who will guarantee his work, or maybe better, purchase a new DFEV.
Good luck









_Modified by chickenfriend at 8:27 AM 1-18-2006_


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## WCHLVR (May 27, 2002)

*Re: (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_Ok. My mistake. You did mention that you replaced the needle valve.
Sounds like your rebuild was perfect.
Good luck.

Thank you for all your help! Sometimes it's just good to get a fresh mind on it!


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## my11g (Jun 23, 2003)

Killer rabbit btw!
I came up with the same idea chicken had. I was thinking your bowl was pressurized. But if you removed the top it would no longer be.
But then again...when you siphon gas...you creat the vacuum via sucking then once you have the process going it continues on its own. Maybe the bowl is presurized...siphon starts and despite removal of top and pressure the siphoning continues...
Either way this is one weird one!
I would find someone anyone with the similar carb. Swap em out and see what happens. At least pinpoint if it is in the carb or elsewhere.


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## WCHLVR (May 27, 2002)

*Re: (my11g)*


_Quote, originally posted by *my11g* »_Killer rabbit btw!

Thanks!


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## WCHLVR (May 27, 2002)

*Re: (chickenfriend)*


_Quote, originally posted by *chickenfriend* »_I think if you could figure out how air is getting into the accelerator pump circuit, and then figure out how the air and gas are getting pressurized in the accelerator pump circuit without the accelerator pump being in the pressure stroke, you have a solution.
I know air gets drawn into the emulsion tube on the way to the main jet. Funny, in this situation, it is like air is getting drawn into the accelerator circuit the in same way.
The air gets drawn in, then somehow becomes pressurized with the gas, then the gas goes out the top and the air comes out the bottom back into the bowl.
I take it air is coming out of just one of the two acc ports in the bowl, then I would assume that port is the pressure relief port for the accelerator circuit, not the intake which should be plugged by the check ball (if there is one).
*Yes, the air is coming out of the left port (when looking at it on the car. I have reinstalled the check ball an it seems to be better. I feel that there should be a light spring to hold it down. I think I may just experiment this weekend and see if that makes a difference (or just makes the car run bad!)







*
The DFEV seems to be pretty well neglected in the carburetor manuals, unfortunately.


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## racevw112 (Sep 16, 2005)

I'm having the same problem on my carb. Looking for solutions.


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## chickenfriend (Jan 31, 2005)

After suffering with the same problems, I think this is what they call fuel percolation.

Carb is getting heat soaked and the 10% ethanol has lowered the boiling point.

Gas is boiling out of the throttle ports into the throttle bore and the accelerator pump nozzle.

You can see it.

It drips all over the throttle plates down into the manifold, and also out along the throttle shaft leaving brown stains and gas smells.

Basically, the engine floods.

Cold start is fine, so is a 5 minute restart after a run.

Hot start after 5 minutes when it is hot outside takes extra cranking, and when the car catches it sputters.

That's because it is flooded.

I don't have a solution yet, but here are some things I am going to try to get rid of it myself.

I have noticed the base of the carb temp climbs dramatically on a hot stop.

Those 4 mount studs are very hot and they transmit heat to the carb base via the nuts and washers. I have a 1/4" spacer under my DFEV, I am going to go thicker. I am also going to try plastic washers under the stud nuts as insulators.

Next strategy is to try shielding. Some sort of heat shield around the carb. Heat shield or wrap on my downpipe.

Fan cooling might be another. Manual fan switch on the dash for the coolant fan, or automatic fan with the mk2 cylinder head external temp sensor-- i like that idea.

The problem is the carb sits over the exhaust and downpipe. When the engine stops, all that heat goes up and is trapped by the hood. Some sort of heat vent in the hood might be a good idea, but I am not into cutting my hood.

If there were some sort of moveable flap on the raintray, it could be opened and the heat would go out the top of the hood through the raintray vents.

Maybe getting into fantasy at this point, but with enough modification, there is probably something that could be done with an electric coolant pump and the routing of coolant through the intake manifolds that have that provision. It would run after shutdown, perhaps concurrently with the radiator fan.


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