TheSamba.com :: View topic - Carb overflowing with gas | Please help! -- S O L V E D ---

Thu Mar 25, 2010 9:06 pm

I recently pulled my car out of hiatus. Rebuilt the 1600 engine and got a refurbished BOCAR pict34-3 carb for it.

Installed it, set it up following this procedure http://www.vw-resource.com/tune-up.html#idle

Fired right up! All was smooth and easy going. Took him for a spin and brought it back home.

Went for a second trip to the store, i pulled up, shut off the car and opened up the engine lid. I saw the carb dripping with gasoline, more like overflowing... It was a lot of gasoline,... a LOT!! picture it as if I soaked it wet with a garden hose and let it drip trough. That much. Falling into the gas pump, intake manifold, tins, etc...

I have read the horror stories about gas on the engine compartment (from misplaced fuel filters) but this too was gas in the engine compartment. I waited for it to dry up and brought the car home.

Once home, there was leaking but not that much, but still, the smell of gasoline was just to be concerned with.

I'm stumped. What could this be? Is there a needle or something i need to adjust?

Additional info: When the car is "cold" or just coming out of cold, runs like a champ, then sputtering starts... i think this has to do with at this time the carb is already dripping rather than the temperature itself.

Thanks for the comments and information.

Regards.

Thu Mar 25, 2010 10:13 pm

Definitely a cause for concern.
The first area that I would check is the carburetor float needle valve. This is located inside the float bowl. It is possible that the valve is stuck in the open position or it is not assembled properly. Check out this article for some more information.
[/img]http://www.vw-resource.com/float_needle.html[/url]
If that is not your problem I would make sure that the fuel pressure is within spec.

It is leaking from the float bowl right? Not from the throttle plate bushing?

Fri Mar 26, 2010 4:37 am

You could have a mis adjusted or bad float as well. The fuel into the carb is NEVER shut off.

As mentioned, check your fuel pressure. Too much can overwhelm a proper operating float valve and properly adjusted float and cause this.

Dave

Fri Mar 26, 2010 5:20 am

I just experienced the same thing with a Kadron/Solex carb that had been sitting about 10yrs. The brass float had a tiny pinhole in it and sank inside the fuel bowl. I made a temporary side-of-the-road patch and it lasted another week before it failed again.

The float and needle on a carb work exactly like the float on a toilet. With the float bottomed out, the needle valve will be wide open, allowing the full pressure of the fuel pump to push as much gas through as it can. The extra gas will go through the fuel bowl's air vent and spill into the carb's throat.

Fri Mar 26, 2010 11:47 am

Thanks a lot for all the replies. will check this afternoon and post findings.

regards.

Fri Mar 26, 2010 3:49 pm

Went outside and took the top part off the carb. Checked everything and all seems to be correct and intact. This is what i cleaned/inspected:

Top
Float
Seal
Float Valve
Butterfly

I put everything back and fired him up. I did noticed that the bowl was empty dry... not a drop (Is this normal?).

Took a few tries to get him running (I figured while the bowl filled up).
I took a chair and sat looking @ the engine. Wanted to pinpoint the failure once it started.

5 min went by, then drip, drip, drip. And I'm pretty sure the dripping comes from a bolt head looking thing at the bottom of the bowl. Part 14 in the diagram below (thanks VW-resource). Called "Main jet cover plug"

I figured, this thing allowing gas to run from the bottom, bowl constantly being emptied, float valve never closes!

Is this a regular fix? Do i need to return the carb to the store?

Thanks for the insights.

Fri Mar 26, 2010 5:16 pm

That's just the float bowl drain...make sure it is snug. It needs a gasket (#15).
I don't think that would contribute to fuel in the crankcase, though.

Fri Mar 26, 2010 8:26 pm

Culito wrote: That's just the float bowl drain...make sure it is snug. It needs a gasket (#15).
I don't think that would contribute to fuel in the crankcase, though.

The fuel all over the place was due to the dripping which was excessive. Will make sure its snugly fit and will report back

regards.

Fri Mar 26, 2010 8:36 pm

Raul you dodged a bullet on that one. Did you have a fire extinguisher?

Check #16.
That is the Electromagnetic cutoff valve (fuel cutoff valve). If you are getting fuel in the crankcase and the fuel bowel runs dry, this valve may be in fail mode. It would allow fuel in the bowel to be siphoned or drain through your carburetor and down into the crankcase. Is it stuck open?

Sat Mar 27, 2010 7:09 am

Yeah, sounds like you've found a starting point. Just to be clear, the carb is NOT overflowing with fuel, rather, the fuel is leaking from the main jet cover plug. There is a rubber o-ring/seal that should be on that. Probably loose plug or broken seal.
Now I read and re-read your post and you never mentioned gas in the crankcase. However, if there is gas in there, while the fuel shutoff and needle valve can be culprits the most likely suspect would be the fuel pump diaphram (bad pump).

Hope it helps!

Mon Mar 29, 2010 5:43 pm

Thanks to everyone for their wisdom... I fiddle with the drain plug and that solved it. Seems someone @ the shop messed with it!

I should have known better... now I know.

thanks once again... i took my car for a spin around town and i could not be happier!

Mon Nov 22, 2010 10:38 am

I think I might be having the same problem. For months now I've been getting terrible gas mileage 19 when I used to get 29. The car is a hard start. We adjusted it some, and now it starts pretty good when the engine is cold. I noticed that if I take it to run errands, by the forth stop, I just might not get him started again, and if I do the entire parking lot will smell like gas. Every additional start is hard until you let the car sit for about 3-4 hours. Then cycle starts anew.

Today I sat and watched the engine after I got to work. I thought I saw smoke. Turns out it was gas leaking out of the carb and vaporizing on the engine. My leak looks like it is coming out of the bolt on part 19, but both sides of the carb.

It is a pretty fast leak. Like this:

http://www.naturefootage.com/video_clips/AG30_016

I got this carb rebuilt from Keith in Dickinson, TX about 2 years ago. It's seen 6,000 miles. 6 months ago a plug blew out of the front of it, and I JB Welded the hole shut.

Should I just buy a new carb or is my problem something else? I'm not sure what made the plug blow out. A VW mechanic told me "that just happens sometimes." But now I'm wondering if something else isn't wrong.

Mon Nov 22, 2010 3:49 pm

When there is a backfire through the carb, sometimes that plug blows out. It's not a fault of the carb itself.
It sounds like your throttle shafts are worn out and maybe there is some residual pressure causing fuel to drip down in to the carb and out along your worn throttle shafts.
If it is a german Solex, I would seriously consider getting it rebushed by keifernet rather than buying a new one.

Thu May 14, 2015 8:20 pm

I am having this problem and have checked the solenoid valve to see it is it working. It is working when I check it but when I shut off the engine there is a stream of fuel coming from the overflow from the bowl. Just dumping fuel. Went back and checked the needle valve and seems to be working. At a loss as what to do next.

Thu May 14, 2015 10:18 pm

70roadster wrote: I am having this problem and have checked the solenoid valve to see it is it working. It is working when I check it but when I shut off the engine there is a stream of fuel coming from the overflow from the bowl. Just dumping fuel. Went back and checked the needle valve and seems to be working. At a loss as what to do next.

Pull the top of the carb off and check to see that the float is actually floating in the fuel in the bowl, if the float is cracked it'll sink and won't properly close off the float needle valve. If the float checks out OK, verify that the curved plastic retainer at the pivot end of the float has the curve away from the float, otherwise it will prevent the float from rising enough to close the needle valve. If neither of those are a problem, please describe how you verified the float needle valve is working.

Fri May 15, 2015 12:06 pm

Im having a similar problem too.i drive the car around to do some erance but but the third time that i park and go the car shuts off on me and it does start but i have to keep that pedal pushed down or it will shut off on me the rest of the way home.Opened the top and there's apool of gas in the Carb,tookit to a local VW autorepair shop and they replaced the float.it ran good for about 1 1/2 hrs. and same problem,gas dripping out of the left & rigth side nuts that are on the bottom of Carb.what canit be??? Someone please HELP

Fri May 15, 2015 6:26 pm

Check fuel pump pressure....

Nuts on lower part of carb are threaded onto the throttle butterfly shaft.