Weber IDF - intermittent fuel leakage from both center/sides

[mikelars]

Question for Weber IDF 40 gurus -

I have an issue where periodically I get a bit of fuel leakage from what appears to be the center of the outside of each carb on both.

I am using a stock mechanical fuel pump, and carb floats are set up as they came shipped from CB Performance with the VW setup. Carbs are basically new with about 10k miles of use.

I have not yet been able to pinpoint exactly where the fuel is coming out - anyone had this problem?

Left

Right

_________________
Here is my 1961 Beetle Restoration:
https://www.youtube.com/playlist?list=PLW_2wBCs4Ny2qXEPvdnfvEzN42T8JA8zO

Here is my 1966 Split Bus - Restoration Channel:
https://youtube.com/channel/UCPBRysmvrJlif2wzwEwiuwQ

2332 Torque Motor Build
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Engine Rebuild 1968cc Playlist:
https://youtube.com/playlist?list=PLW_2wBCs4Ny1JbZ2EgJQQ2awfo0koZRqz

[Dougy Dee]

Could be the cover for the pump jet diaphragm. Possibly the cover is not flat or screws have loosened off.

[RandyV]

Ya, accelerator pump area could be culprit since it's happening on both sides. (Both diaphrams torn or loose would be odd though)

Another couple thoughts......

#1.) Use a mirror to view back there & see if you can duplicate by just revving the motor??

#2.) Use/borrow and old GoPro & mount it somewhere in there where you could drive under load to duplicate ?? (If it'll focus so close, the wide view should give you a good look)

Curious to find out what it is.

[mikelars]

GoPro is a good idea - I need to figure out a good way to Mount it.

I don’t really want to start disassembling things just guessing. I had thought about setting the float levels a bit lower.

The fact that the fuel comes out of the center made me think it was coming out of the accelerator pump diaphragm mechanism.

Of course having fuel come out in the engine compartment is not a comfortable thought, though it is not every time I drive, and not very much fuel.
_________________
Here is my 1961 Beetle Restoration:
https://www.youtube.com/playlist?list=PLW_2wBCs4Ny2qXEPvdnfvEzN42T8JA8zO

Here is my 1966 Split Bus - Restoration Channel:
https://youtube.com/channel/UCPBRysmvrJlif2wzwEwiuwQ

2332 Torque Motor Build
https://youtube.com/playlist?list=PLW_2wBCs4Ny2HwsKM9QT4LFpcSqP3QG0p

Engine Rebuild 1968cc Playlist:
https://youtube.com/playlist?list=PLW_2wBCs4Ny1JbZ2EgJQQ2awfo0koZRqz

[mikelars]

Ok, I put 2 “Accelerator Pump Diapers” on there - let’s see if anything comes out

_________________
Here is my 1961 Beetle Restoration:
https://www.youtube.com/playlist?list=PLW_2wBCs4Ny2qXEPvdnfvEzN42T8JA8zO

Here is my 1966 Split Bus - Restoration Channel:
https://youtube.com/channel/UCPBRysmvrJlif2wzwEwiuwQ

2332 Torque Motor Build
https://youtube.com/playlist?list=PLW_2wBCs4Ny2HwsKM9QT4LFpcSqP3QG0p

Engine Rebuild 1968cc Playlist:
https://youtube.com/playlist?list=PLW_2wBCs4Ny1JbZ2EgJQQ2awfo0koZRqz

[mikelars]

What exactly makes the accelerator pump mechanism kick in? Is it more vacuum from the intake manifolds or the turning of the throttle from the linkage?

I have never watched the accelerator pump in action….
_________________
Here is my 1961 Beetle Restoration:
https://www.youtube.com/playlist?list=PLW_2wBCs4Ny2qXEPvdnfvEzN42T8JA8zO

Here is my 1966 Split Bus - Restoration Channel:
https://youtube.com/channel/UCPBRysmvrJlif2wzwEwiuwQ

2332 Torque Motor Build
https://youtube.com/playlist?list=PLW_2wBCs4Ny2HwsKM9QT4LFpcSqP3QG0p

Engine Rebuild 1968cc Playlist:
https://youtube.com/playlist?list=PLW_2wBCs4Ny1JbZ2EgJQQ2awfo0koZRqz

[Dougy Dee]

Could also be the inner throttle shaft area. No bushings or bearings there.
Are these Weber or HPMX?

[modok]

Get that braided hose the heck away from your voltage regulator.

[mikelars]

[mikelars]

[mikelars]

Ok, the results from the “accelerator pump diaper” are in.

What do you think? Right side only and only after engine fully warm:

_________________
Here is my 1961 Beetle Restoration:
https://www.youtube.com/playlist?list=PLW_2wBCs4Ny2qXEPvdnfvEzN42T8JA8zO

Here is my 1966 Split Bus - Restoration Channel:
https://youtube.com/channel/UCPBRysmvrJlif2wzwEwiuwQ

2332 Torque Motor Build
https://youtube.com/playlist?list=PLW_2wBCs4Ny2HwsKM9QT4LFpcSqP3QG0p

Engine Rebuild 1968cc Playlist:
https://youtube.com/playlist?list=PLW_2wBCs4Ny1JbZ2EgJQQ2awfo0koZRqz

[virusdoc]

What is your fuel pressure, and how recently did you measure it with a gauge?

My 40 IDFs were doing the same gas leak thing and my fuel pressure was over 6 psi, overpowering the needle valves and filling the bowls until fuel leaked out the top. I was also using a stock mechanical fuel pump, and I needed to add almost 1 mm of gasket underneath it to bring pressure down to a stable 3-3.5 psi. Make sure you are using the correct length pushrod and bakelite spacer--they are not all the same length.
_________________
1976 Convertible Super Beetle, "June Bug".
FI-->34PICT3 carb conversion-->now dual 40 IDFs
Self-rebuilt 1904 (after totally botching a 1641 rebuild, cussing a lot, and throwing lots of cash in the fire)

[mikelars]

[74 Thing]

Tee in one of these and run it in your driveway and see what the pressure is and adjust accordingly:
https://harborfreight.com/fuel-pump-and-vacuum-tester-62637.html

Could be leaking from one of the screws as well if an o ring needs replacing.

You need to run it and see if you can feel where it is wet and fix it.

[virusdoc]

[mikelars]

Ok, I have ordered a pressure regulator I can put in right before the T in the fuel line, and a gauge so I can check the pressure. I am probably converting to an alternator anyway, so I would change out the pump at that point anyway.

So what is the ideal fuel pressure right before the T split out to dual carbs? Is it 2 lbs pressure or 3.5 lbs?
_________________
Here is my 1961 Beetle Restoration:
https://www.youtube.com/playlist?list=PLW_2wBCs4Ny2qXEPvdnfvEzN42T8JA8zO

Here is my 1966 Split Bus - Restoration Channel:
https://youtube.com/channel/UCPBRysmvrJlif2wzwEwiuwQ

2332 Torque Motor Build
https://youtube.com/playlist?list=PLW_2wBCs4Ny2HwsKM9QT4LFpcSqP3QG0p

Engine Rebuild 1968cc Playlist:
https://youtube.com/playlist?list=PLW_2wBCs4Ny1JbZ2EgJQQ2awfo0koZRqz

[virusdoc]

[Ohio Tom]

No reason for more than 2.5psi.

Is she hard to re-start sometimes?
Acts flooded?
If so, then fuel pressure might well be the issue.



If it's just the accelerator pumps leaking, then it's time for a re-build kit and new pump diaphragms. They do fail and need replaced every so often. They are made of rubber and some kinds of fuel can eat them.
Water can corrode the center rivet as well and make them leak.

[mikelars]

[mikelars]