Which strimmer?

[YFS]

I sprayed carb cleaner into the choke inlet, put fresh petrol in and tested it without the strimmer-head attachment and I thought it was revving ok.
I put the strimmer-head attachment back on and it would not rev again. I cannot see how that was the problem. It does seem that when the petrol level is not right to the top, it stalls. Perhaps there is a problem with the petrol pipe?
If I pump the primer bulb without fuel to the top, it just pumps air.
I will check things when the rain stops