B2 GL5 running problem

[inthe weeds]

i have a GL5 auto on a carb and its been running fine since i got it about 1000 miles ago,

now i start it up and it runs but as soon as i accelerate it goes to die, when it warms up its better and drives fine for 5/10 mins but then dies later,

the only way to keep it going is to pump the gas and that works for a while then it seems to be fine again

its a very erratic problem ... can anyone share any thoughts?

ive took off and stripped the carb and there is no poo in there,

cheers Mike