Thanks Deputy,
The temp here in Pretoria is in the early 70s at the moment. the engine was not worked hard and did not seem to run hot at all. I could still touch the valve cover after the 3Min run. What I find weird is that it runs fine at full throtle and at idle but likes nothing in between. I checked nipples -Facing the engine The right line goes to the tank via the check valve for press and the left one from the tank to the engine via fuel filter. I have also just released the press now which has held for two hours.