I've just reassembled my mk.3 "project" bike following a comprehensive strip-down, clean and renewal and now when I turn the fuel tap on, fuel IMMEDIATELY p*sses all over the place from the vent tube connected to the carb bowl. Like an idiot I didn't note where all the various hoses were connected to before I started because it all looked pretty straightforward (famous last words) and now I'm wondering if I've done something really dumb. Please could someone (anyone!) take a look at the linked photo and tell me whether all of the hoses are in the right place and if so, any ideas on what else could be causing this? Stuck floats or needle valve? Something else?

Many thanks for all advice/comments:

Carb image : http://i26.photobucket.com/albums/c133/ ... bSmall.jpg

Most likely is float valve not correctly seated or floats put in wrongly. Need to take carb apart and re fit. It is not wrong fitting of vent tubes.

[b]SemiSaneSteve :[/b]
> I've just reassembled my mk.3 "project" bike following a comprehensive
> strip-down, clean and renewal and now when I turn the fuel tap on, fuel IMMEDIATELY
> p*sses all over the place from the vent tube connected to the carb bowl. Like
> an idiot I didn't note where all the various hoses were connected to before
> I started because it all looked pretty straightforward (famous last words)
> and now I'm wondering if I've done something really dumb. Please could someone
> (anyone!) take a look at the linked photo and tell me whether all of the hoses
> are in the right place and if so, any ideas on what else could be causing this?
> Stuck floats or needle valve? Something else?
>
> Many thanks for all advice/comments:
>
> Carb image : http://i26.photobucket.com/albums/c133/ ... MCarbSmall.
> jpg


I get a similar problem with mine if it's been standing for a while, with the float needle not seating correctly. Try turning the fuel tap on, and when the fuel starts to leak out, tap the float bowl gently with a bit of wood, or something not to hard. If this doesnt work, Something is wrong when you re assembled the carb, as Knackerd has said.

i did notice from the pic that there was a lot of dirt around the carb, i was wondering if you might have got some of that in the carb on reassembly and that is what is holding the needle open. your best bet is to wash the bike and strip the carb again. Jon

just a tip,when you've checked the fuel shutoff/float needle valve and cleaned any debris out of the seat or off the top off the valve,re-assemble and blow down the fuel inlet.with the float lowered you should here the air passing through the valve,lift the float upwards,the valve should seal up and you shouldn't be able to get any air through the valve

Thanks for all the advice guys. It was the float valve that was stuck. Bike now runs but erratically and won't idle (idle screw makes zero difference). Despite 3 thorough cleans there's obviously still crusty gunk in there somewhere. I'm starting to think that this carb is heading for the bin

No need to bin the carb. There's probably just some stale petrol that's formed nasty yellowy deposits in one of the channels. Carb cleaner won't shift it, but getting the card ultrasonically cleaned will.

I had grief with this on a set of carbs a while back and doing this sorted it out a treat.