Need some help from you clever people out there with our 2.0 petrol CU Aircooled engine.
Just completed top end rebuild and put engine back in last weekend but can't get it started

I've checked the fuel feed to the carbs and it is dry as a bone so took pipes off fuel pump (mechanical) and tried turning over engine to see if sucking and blowing - no obvious signs of either when putting fingers over the inlet / outlets.
So, no fuel getting through. I changed fuel filter and sucked through by mouth at fuel pump end (not nice or recommended) so doesn't appear to be a blockage in the fuel pipe.
Problem therefore presumably at fuel pump. I stripped this down during the rebuild and it was like brand new - all diaphrahms fine, etc and push rod looked okay. I checked that it sucked and pumped by manually operating the lever and it was fine.
Been to Bus Types at weekend and was talking to someone there who said the timing could be 180 degrees out so the pushrod is trying to suck from carb not blow and therefore as only designed to work one way, would explain why no suck or blow? Also, when I was turning the starter, I noticed a large fuel leak coming from the oil cooler - from the new seals by the looks of it

Has anyone got any thoughts on this as I will lose the will to live if I have to take the engine out again!

I'm sure there will be some clever person out there who knows the answer...
