Weber 44 IDF / fuel pump problem

Flat4ever · 06:05 AM

I run a 2.0 914 from 1973. It is carbed with two 44 IDFs and a little facet fuel pump. I noticed a problem: when I stop the engine, fuel is leaking in ONE carburetor body (IDF have 2 bodys) and at the pump accelerator command...

It happens not only when engine is hot but also when it is cold: I start engine, it runs 3-4 minutes, I stop it and after fuel is leaking

I changed this carburetor (I have an other one) and it is the same, exactely in the same carb body !

I do not understand anything .... too much fuel pressure ? Needle valve problem ?

Help ! I do not want to burn with my car !

You can see a fuel drop in the right body and the reflection of the fuel on the throttle valve...

I want to understand Mulder said ...

John Rogers · 10-28-2003, 07:14 AM

Since it appears you are a novice with the carbs, I'd recommend finding a shop to overhaul them and set the float height and do all the other things so they will operate correctly. Since you have one of the small Facet pumps I am guessing fuel pressure is okay as I use one also. The arrow is pointing to the check ball valve ( I think) for the accelerator pump so there may be a problem with the pump, gasket or other related area.

Flat4ever · 11-05-2003, 06:03 AM

Thanks john,

Yes I am novice with the carbs.
Some precisions: It is not a fuel pump pressure or needle valve problem. It happens when the engine (and fuel pump) are cut off: the carb tank completely empties in only 4 hours !

Mystery...

Scooter311 · 11-05-2003, 06:23 AM

Hiya Flat4
My webers leaked horribly when I first bought my car. The acellerator pump gaskets and diaphragms were shot and did the same thing. Could this be your problem? It was easy to rebuild the carbs, and inexpensive also.
Cheers!
Jeff

Dave at Pelican Parts · Dave at Pelican Parts's Garage

I'm not sure what you mean by the "carb tank"--do you mean the main fuel tank (lots and lots and lots of fuel!!!) or the "float bowl" in the carburetor? If the latter, check your throttle linkage. I have heard of occasions where the linkage was adjusted a little too tight, and the vibration of the engine running was enough to activate the accelerator pump and dump quite a bit of extra fuel into the carb.

It's also probably worth tearing the carbs down and cleaning them up and replacing all of the seals and such.

Then again, I am an FI guy and not by any stretch of the imagination a carb guy....

--DD

Flat4ever · 11-05-2003, 10:50 AM

The latter (float bowl in carburetor) arrowed on the pic. The linkage adjustement is a good idea. I will inquire this...

Thanks and sorry for my poor english...

maf 914 · 11-05-2003, 12:47 PM

First make sure your carbs are in good condition and not leaking because of old gaskets or o-rings.

Then, using a Weber manual, check the float level adjustment. I once had a problem with my 40 IDFs that sounds similar to your problem. Fuel was dripping directly into the carb throat. You could look down into the throat while the engine was running and see drops of fuel falling. After reading my collection of Weber manuals I took the top covers off the carbs and set the float levels, which stopped the fuel drip.

By the way, your English is fine. Welcome to the forum.

Mike

DDS · 11-05-2003, 03:48 PM

Hi Flat:
Agreed, your English is fine. You did say it did this when the car was not running. Weird.
Where does the fuel leak from when the car is not running?
If the entire bowl is draining with the engine off, it must be siphoning through somewhere lower down than the level in the bowl, like the transition or idle orifices. If you can see fuel on the butterfly it must be the transition orifices as the idle ones are below the butterfly. (at least on My DCNFs they are) Rebuilding the webers is a good learning experience in any case.
I wouldn't think it would siphon, I think there's an air correction jet or adjustment that should break the siphon and prevent that. Maybe that jet is clogged. Either that or the float bowl is becoming pressurized somehow.
I'll have a look at one of my weber books tonight and study the IDF to see if I can hazard a better guess.

Dave

Flat4ever · 11-07-2003, 02:51 AM

I can see fuel ON butterfly. At the beginning of leaking, it makes abourt 1-2mm of fuel ON the butterfly.

You can see the reflect on picture, in the right body

DDS · 05:22 AM

I've only gotten really intimite with DCNFs, but from what you describe the problem is in the idle circuit which supplies the idle and transition orificies - OR.................. AHA! is that a choke/enrichment circuit I see at the top of your photo? I didn't know IDF's had those. I just looked quickly at a dwg for the IDF - the one I saw had a blanking plate on it, but yours appears to have a choke/enrichment circuit just visible at the top end of your drawing, and it looks very similar to the DCNF. If so, that's probably your problem - it is incontinent. That circuit can be quite troublesome.
Take your extra carb apart and get familiar with how that part works, it is like a seperate crude mini-carb, with a pair of spring loaded pistons sealing passages to what, IIRC, is a seperate orifice for idle enrichment. The choke cable opens those pistons to dump extra fuel into a cold engine. Its valve seats way down low, so it would drain the float bowl if the valve wasn't seating, no siphon mumbo-jumbo. Most guys blank that circuit off and don't use the choke.
You have to carefully pry a springy brass washer out of the top of the carb to get the piston out. Mine were completely siezed and full of crud.
Good luck.

Later... the only thing that doesn't jive with the choke hypothesis is that the fuel is pooling on top of the butterfly - I'd bet the choke orifice is below it. This points back to the idle circuit. As others have said - they need to be torn apart and cleaned and rebuilt. They'll drive you crazy otherwise. Once you become familiar with the carbs it can be done very quickly.

Dave
Dave