GTD warm starting problem

Hi all, 

Just finished my petrol to GTD engine swap and all works fine apart from trying to start the car when it has been running for 10 minutes on idle or so. It will be running good until I switch it off and then try to start it back up again. When I do so, it will crank over but nothing will happen, it doesn't even sound as if it's trying to fire. 

I'll then go back out half an hour to an hour later and it'll fire up basically straight away. And the same happens when I turn it off and then start it again. Any help will be greatly appreciated!

Travis

could be a compression issue, or the fuel solinoid on the pump