Golf clipper convertible 1800 running problems HELP!!

Hello all can any one tell me what the component is that sits between the fuel pump and the carb, it has one pipe in and two pipes out one to the carb and the other looks like a return to the tank. the reason i ask is that my car will idle nicely and drives on light throttle but as soon as you give it full throttle is starts to miss and then its as if there is no fuel.
I have replaced the following parts
distributor cap, rotor arm, spark plugs and coil, also new mechanical fuel pump, fuel filter and it had a new tank and filler neck as part of getting it running after being laid up by previous owner. it is also fitted with a weber with manual choke.
i think the component i am enquiring about maybe the problem but what is it.
Any help will be much appreciated as i am at my whits end.  
cheers in advance chalk.

Sounds very much like carb problems,The main jet could be blocked and or the accelerator pump jet,quite likely if the car has been laid up for a while.
As for the other thing,I think it just holds fuel to stop all the fuel self returning to the tank,so there is nothing really to go wrong with it,but i'm not 100 percent on that
I would give the carb a good clean out and go from there,Best of luck mate.                       
                                     Baller

Cheers Baller,
                    i have cleaned out the carb and still no joy but after much investigation with parts departments at VAG dealerships, i think it is the fuel vapor resevior (the part i didnt know what it was) i was pointed towards it by MKOne on another thread just getting the hang of this forum malarkie, but cheers for replying, i have a weekend free as the dealer has to specially order one for me from germany.
Cheers Chalk

Hi Chalky, I've got the same motor as yourself & as I was in the breakers getting other parts I spotted this. My car didn't have one so I got this as well. From what I've been told, it's more or less just a holding reservoir for the fuel. I see there isn't any way to open it & clean it out but If your having to wait a while for it, pop into your local breakers & see if you can get one, it should only be a couple of quid. You might be able to get one off a newer model car as mine came off a jetta & it's just the same so try any newer VW with a carb.
Cheers

Cheers mate i will put on my wellies and go a hunting, strangely enough i tried to get the car running the weekend and all was good till about a mile in and nothing, so i checked out the fuel delivery and found i had no fuel being pulled through the inline filter so set to work on the sender at the side of the road, a few hits with the hammer later and still nothing but after reconnecting the sender electric's she started and the fuel delivery was good. go figure. any way driven her up to a fast speed's and she has been fine  fingers crossed.
Chalk

Hi Chalky, I too had all these problems with my Mk1. I was ready to commit harry kiri on more than one occassion as whenever I took it to the garage they couldn't get it to do the same thing. Even after changing the fuel vapour thingy on the top of the engine(looks like a steel fuel filter), just as I was about to give up I took the mechanic out and floored the motor…..she suddenly started doing it. Now….I'm not sayin it is this, but it has worked for me…….. I blew the fuel line out, back into the tank(take the fuel cap off first), it ran for 2-3 weeks without a problem, then it did it again, repeat the process and it was trouble free for the next 2-3 weeks, eventually I took the fuel pick up pipe and sender out of the tank(located under back seat) and drilled the end of the pipe out so as to give a bigger fuel pick up. Touch wood I have had no problems ever since I did that, and she runs like a dream, even after wellying her.
The mechanic did state that it may be because I have a Weber conversion on her that there wasn't enough fuel getting through.
Hope this helps mate, it worked for me anyway.
Good Luck
Andy

Clackers, cheers mate that makes a lot of sence i am going to get the car in to our work shop and blow the lines out and drill the sender unit.
Cheers for all help

Chalk

Chalky, make sure you drill the end out and don't cut the end off, if you cut the end off your fuel pick up will be wrong and you'll run out of petrol when you've still got quarter of a tank showing. It should make a difference…..let me know how you get on mate.
Cheers
Clackers

Cheers mate, will let you know how i get on.
Chalk