Might be worth taking the pump off and having a look inside it? I would guess if there's anything wrong with it, either the diaphragm will be cracked and leaking, or it just won't be moving far enough for some reason. On one I had which gave up the ghost, the nipple (ha!), on the end of the rod which is attached to the diaphragm, had been worn away by the fork in the pivoted arm.

you could do what was suggested further up, before and rig up a fuel tank (above the carb so gravity takes fuel to it in plentiful supply and that would tell you if its the carb, or not then you can play the elimination game

and if it is running fine after doing what was suggested, take a pipe from bottom of the fuel pump into a jerry can and see if it sucks fuel thgouh ok (see if the problem persists) and then if it doesnt then its at the tank end or in the pipe somewhere, i had a fuel leak in my car, never realised until the pipe completly perished !

So what was it in the end?

I don't know if I've cured it yet, as I've not had a reason to replicate the conditions in which it happened. I did go to Lincoln in it this weekend, without problems, but even the stretches between roundabouts on the A46 are not really long enough to confirm whether or not the new fuel pump I fitted has cured the problem. I'll find out on Friday on my way to Registers...

dont forget the door

Fear not. I've got it out of the garage and given it a quick wash and polish this morning.

Good good ill be able to slerp tonigjt lol. Thank:)