Thanks guys,

I haven't had a chance to check all of these things yet.
It does sound like the pump or reg may have been gummed up or had something in it.

The black injector cap is a little loose. I haven't looked at it in detail, but it moves side to side easily. (in/out is firm, no movement)

As mentioned i'll go round all the bolts and seals and try it again.

Is there an easy way to find a leak?
When you start to look at all the possibilities it becomes a little daunting