Problem identified - Stalling under heavy breaking... Why?

[MacColl]

This thread has something about float height..
http://www.clubgti.com/showthread.php?1 ... TML-refurb

The floats are on thin metal that is iirc very easily bent into position. I remember using a 7mm allen key as my gauge.

[Eurobox]

Today I whipped out the jets just to blast (again) with carb cleaner just to be sure and to double check the sizes for the 1.8 and I believe them to be correct?

Primary:

Idle 55
Air corrector 145
Emulsion F-30
Jet 117

Secondary:

Idle 60
Air corrector 200
Emulsion F-33
Jet 127

Then... things got worse and I snapped off the insert part of the primary emulsion where it goes into the air corrector... D'OH! I WAS trying to be careful but as I slid the air corrector off I noticed that one side of the insert (the bit thats now detached) was lying inwards, so I carefully tried to tickle it back straight and I knew it would go! bugger!

Will this still work ok if I pop it back in or will I need to replace the emulsion tube?

Or is it probably going to be a better idea to replace the lot?

[MacColl]

Firstly your jets seem to match the Weber guide I have. The wire is an earth to the head if thats what you mean?

It looks like it's just the emulsion F30? that needs replaced.

fast road will have one here..
http://www.fastroadcars.co.uk/shop/inde ... oductId=81

I should have a spare but would have to check later in week probably Wed once I'm near my workshop.

Have you had the carb in pieces? like stripped and re-built? I bought a service kit from fast road for mine bit of a fiddle but actually enjoy doing it.

I'm still wondering if when you brake the carb is touching the bonnet and creating a leak? Any kind of air leak at the base would pretty much cause stalling. I do recall putting a bead of hylomar on all mating surfaces of the adaptor plate/inlet manifold other than the actual gasket that touches the carb.

IIRC I bought this new carb block..
http://www.fastroadcars.co.uk/shop/inde ... ductId=101

Sorry if I am repeating what you already checked. As I've said I think getting someone in who knows about carbs/80's vw's would probably give some insight fresh pair of eyes and ears and all that.

[Eurobox]

The broken emulsion is the F-30 one but I stuck it back in and still works, well it still works the same as before, like no change lol.

I've been running it since I fitted the new rubber mount without the airbox fitted so it's not touching the bonnet at all anymore and it's still dying when I brake. I've been looking into it a bit more and it only dies when I brake when the car is in motion. It doesn't die when I touch the brake stationary, so something is moving forwards when I brake causing it to die.

The carb mount is totally air tight too, that I'm confident about. I can't get it to die if I try to move it about whereas it would have with the old rubber mount so I'm thinking this carb has more than one problem, be it jets, emulsions, vacuum leaks or float height issues so I've decided to get another weber and try that instead of messing about with this one, and if it works fine it'll be end of headaches.

Is this Hymolar stuff like instant gasket?

Oh and just to add it fires up instantly from cold but if I switch it off after a run when up to temp then try to start it (like when I stop to fill up) it takes ages to fire up and runs rough like it's running on 3 for a few seconds. It's always done that, not just since recently and stinks of fuel for a while too? Does this ring any bells?

[MacColl]

Hylomar is just the blue instant gasket stuff which in all honesty probably isn't needed and isn't always good for rubber parts. I put some on the adaptor plate mating surfaces for insurance as just couldn't find the problem with mine at the time. I was at your stage where I couldn't understand what was going on and wanted to give up

Is your adaptor plate nice and tight on top of the rubber base? and then the carb itself with gasket? that gasket block I bought was actually for a Polo I had.

Have you serviced the car? like oil, filters, dizzy, rotor arm, ignition leads? how are your rubber fuel pipes? Swirl pot? All the way back to the fuel pickup inside the tank? metal fuel lines? something could be moving when braking and casing starvation? The carb might be running too rich follow the guides and lean it out and keep checking your spark plugs.

I think fitting another carb could well be worth any more hassle

Failing that take it to an old school garage

[Eurobox]

Have I serviced it? I certainly have.

I started with cleaning out the tank of rust then popped a few large magnets close to the pickup pipe, then blew the fuel line through with a pump, replaced the inline fuel filter, blew the pipe to the pump out, replaced the pump with a new one, blew the pipe from the pump to the carb through. There is no swirl pot, it's just a direct fuel hose from the pump to the carb with no fuel return.
Then I stripped down the carb and gave it a good seeing to, rebuilt and refitted with new rubber mount. All hoses are in good condition.

Then I replaced the coil, leads, rotor arm, dizzy cap and plugs.

Today it started to splutter and hold back for a while so I gave it a bit choke and it settled down again then when I got it back home I switched off and had a look into the carb because there was a stream of smoke coming from the air correctors and looking into the barrels I could see the fuel pooling over the two closed butterflies quite deep too probably around 10mm deep , also it was dribbling out of the side of the carb somewhere I couldn't tell where and the cardboard gasket was completely soaked with fuel. This didn't look right to me, does that sound normal to you? To me it makes me think it's because there's no fuel return but back in the early posts in this thread I was told it didn't matter.

There is no swirl pot which I believe is where the fuel return pipe should come from?

Would fitting a Y piece in the fuel line close to the carb with Y piece pointing against the flow from the pump with a return hose reconnected to the return pipe (that has a bolt in it to blank it by a previous owner for some reason?) work just the same to relieve fuel pressure from the carb?

This is why I think it's filling with fuel after I've switched off and I reckon it'll do the same with the new carb.

My thinking is that having a fuel return with a restrictor may also help regulate the fuel because I've just thought that when I'm braking I may be causing a momentary hesitation in fuel delivery ie when I brake things go forwards - the fuel in the fuel line which runs straight back to the carb over the rocker cover...

Does this sound like I'm onto something here or am I talking bollocks?

[MacColl]

I think you might be on to something

Firstly read this..

http://www.vwgolfmk1.org.uk/modules.php ... uel+return

It discusses running without the swirl pot but keeping a return.I would prefer to have some sort of return using either a swirl pot or a T-piece as they discuss.
There are T-pieces from the likes of Fast Road if you think you need a specific size to allow good fuel in pressure..
http://www.fastroadcars.co.uk/shop/inde ... t&catId=10

or
http://www.webcon.co.uk/

Also if you look at the inside of an original swirl pot it has a very restricted return..
http://sciroccoregisterforum.co.uk/carf ... pot#p42501

was in this thread also interesting read..
http://sciroccoregisterforum.co.uk/carf ... pot#p92383

I don't think I had enough restriction on my return so reduced the plastic return pipe with an inner sleeve of plastic vac pipe. I actually have the opposite problem that you have, basically overnight the fuel runs away down the return so I always have a bit of fuel starvation for the first half minute or so. I also think my fuel pump is tired and would benefit from new one. I'm wondering if you are simply over fueling and the engine is overwhelmed when braking and the residual fuel when starting warm is flooding the carb

It's all a bit confusing discussing this on here but I hope you can get to the bottom of this finally, you've got me thinking that my weber isn't fully running to it's potential

[Eurobox]

Yeah it makes sense doesn't it.

I was thinking the exact same thing in terms of a restriction - using an inner sleeve made from a piece of vac pipe.

I'm going to swap out the weber anyway and I'm also going to fit a return line via a T or a Y piece with a restrictor in place.

I'll probably do this at the weekend and I'll get back and post my findings.

[Eurobox]

Ok I've dug out a Y piece and a length of fuel hose this evening and inserted a 'restrictor' which I made from a blue spade crimp connector of all things, I snipped the spade end off and this went in snugly, so hopefully it'll work ok. I'll fit it tomorrow.

[Eurobox]

Ok so quick update...

It's sorted!

I fitted the above spade connector end into the return hose but that turned out to be not very restrictive at all so I fitted an additional slightly smaller one and that did it. The car fires up instantly from hot or cold now and doesn't flood, also idle problem has gone and idle drops to 850-900 rpm and remains perfectly stable when I lift off the gas and apply the brakes...

and to think back after all that it was what I first suspected after all, I was just so caught up in the vacuum leak idea that I completely overlooked it and it wasn't until it couldn't have been anything else that I turned my attention back to the fuel return.

Now that I've refitted a fuel return via a Y pipe the fuel can flow into the carb and keep it regulated just so with the restrictor, but when switched off it can relieve the pressure at the carb which was flooding it causing it to not start properly.