Fuel leaking from vacuum take off

[Norman AndersonParticipant]

Hi folks,

Hope this isn’t a stupid question. The car is fitted with a 123 distributor, so no vacuum input is required. I didn’t do anything with the vacuum takeoff on the carb, and the car seemed to run fine, but had an annoying odour of fuel. I’ve noticed that after cranking, fuel dribbles from the vacuum takeoff. It’s a new rip off Solex 32 carb. Should I seal off the vacuum takeoff as it’s not being used? Can’t find anything on the myriad of Solex forums out there. Thanks for your help.

[Norman AndersonParticipant]

Further to my last. Sealed off the vacuum tube. Cranked the engine, a fuel was still pooling on the heat shield below the carb.

Took the air filter off and looked down the carb throat with the throttle butterfly open. Never seen anything like it. An absolute pool of fuel down there! What on earth can be going on?!

[AlistairParticipant]

Is the butterfly spindle the source of the leaking petrol? I had a carb that had a worn spindle and was pouring fuel. The spindle has worn the carb and required re-bushing.
Alistair

[David FaulknerParticipant]

Is the float stuck open Norman?

Try ‘tapping’ the float chamber to get it to come up.

[David FaulknerParticipant]

Grr editing the post I lost internet connection.

OK are you sure the carb isn’t leaking between the top and body?

On my ‘Copy’ Solex I found that the top wasn’t flat and would never seal….

I found that there was a gap of 0.20mm at the accelerator pump jet area reducing down to 0.10mm at the float end of the top section. Now the gasket used between the top and base is only 0.20mm thick and fairly stiff so was not going to fully take up that gap when the top is fitted and tightened, no matter how hard you try.

Once lapped flat with 600 grit, leak cured.

[Norman AndersonParticipant]

David and Alistair, thanks for your responses.

It shouldn’t be leaking from any worn areas, as it’s a brand new carb.

I took the air filter off and dried things out. Cranked it with the throttle wide open (as it was most likely flooded). Never, ever seen anything like it. The moment it fired, a torrent of raw fuel shot out of this tube!

No wonder it was absolutely bathing in petrol! Looking at the parts diagram (and David’s excellent website), it would seem to be some sort of ‘balance’ tube for the float chamber? Could a stuck float do this? Must be a seriously crap copy of a Solex carb ☹️

[Roger GrixParticipant]

If it’s not a sticky float, or a bad needle valve, have you done any work on the fuel pump?

Roger

[BernieParticipant]

I

Norman,

I believe the prine function of that tube us to equalise the pressure in the float chamber with atmospheric.   In that case fuel should certainly not come out of it unless the float chamber is filled to the brim and still accepting fuel.

That does imply a sticking  float as previously suggested  but it could also be a faulty needle valve or incorrect setting of the float level.

If the carb previuosly worked  without floodiing, the float level is probably ok so is the needle valve stuck or jammed with debris?

B…..

[AlistairParticipant]

I also had a problem with a new Carb for my Light 15. The small flap that sits above the float had become dislodged and held the float down so it would not cutoff the fuel supply to the chamber. The result fuel everywhere. Once I had taken off the top of the float chamber the problem was seen and easily fixed.

Alistair

[Norman AndersonParticipant]

Just back from the Netherlands. Lifted the top off the carb. It looked like the float was stuck in the chamber at an awkward angle, so maybe it was jammed, or it was the small flap as Alistair suggested. Hard to tell. Anyhow, lifted the float out to find a whole lot of black sludge at the bottom of the float chamber! No idea as to how this has happened as all the lines are new, and there are two filters in the line.

Cleaned it all out, and it now runs fine. I’ll keep an eye on that float chamber.

[BernieParticipant]

Norman,

Black sludge – possibly the fuel attacking one of your “rubber” hoses.  Were it mine, I would want to check them (inside as well as outside)  for any signs of deterioration or perhaps “tackiness” in case they are incompatible with modern fuel.

B…..

[Norman AndersonParticipant]

Hi Bernie,

The only rubber is a very short section from the fuel pickup to the first filter. It’s a brand new Citroen part from Franssen. The rest is either copper or SS braided PTFE – all brand new. The engine was overhauled by Michael Geary, perhaps there was a bit of crap in the fuel pump? (Not to speak badly of Michael – he did a beautiful job).

Cleaned it all out and refitted the float. All was good until yesterday. It looks like the float has jammed again. I still have the original carb, which is beyond economic repair. It dig out the original float and see if it’s better behaved than the new copy. It will also be a good opportunity to check for sludge!

[BernieParticipant]

Norman,

Sounds like a plan but be aware that, if you swap the floats, a different float might affect the fuel level and may require adjustment to the needle valve height.

I would be tempted to try and determine the cause of the “jamming” and, if possible, address that first.

B….

 

[Norman AndersonParticipant]

No new debris in the float chamber, which is good news. Dug out the old float and lever from the original Solex carb. What a work of art compared to the cheap Solex copy. Fitted it to the new carb and all appears to be good.

Sure enough however, there is evidence of a wet gasket just where David had the issue with his copy Solex, so it may well have a similar issue there, and could explain the constant petrol odour. So thanks for the info David.

[David FaulknerParticipant]

Your welcome Norman, hope you sort it so it works properly but it may still tend to run ‘rich’, mine does

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