Strange fuel problem

[Martijn]

I have got a strange problem wit our Fordson N.
It is fitted with a glass bowl type fuel tap.
When everything is fitted as it should, and the petrol tap is opened, no petrol gets in the glass bowl.
Looks like fuel tank is emty, but it is'nt..
Then, when I loosen the screw a bit that's holding the glass bowl, fuel starts to run in the bowl.
Nothing blocks the canals of the fuel tap... It lookes like there is some kind of air lock somewhere but I can't find it..
Please, can somebody give me an advice?

Greetings,
Martijn from Holland

[tmc]

Is the carb bowl still full ? sometimes the glass bowl doesn't fill until the air can move out through the carb.
run some fuel out of the carb drain and see if the glass fills then.

[Dandy Dave]

Yup. If the carburetor is full, and the float and needle has it sealed, the fuel will not flow until you start it and the carburetor level drops enough to open the valve. Good thing is, If it is air tight, it will be fuel tight. Dandy Dave!

[oehrick]

You can check it by opening the carb drain, if its muck in the pipe or something else, vibration from starting may agitate it enough to let fuel flow and give you a false diagnosis.............

(Edited due to being a twit) Ooops, Sorry tmc, somehow missed your post saying the same thing