Update. I think you were right on Chris. I was following the fuel, clear up to the low pressure pump but very aerated and white from the outlet of the high pressure pump. (see picture) The hose that connects low pressure and high pressure pump shows signs of cracking and wear, unfortunately I have to wait for the Yanmar parts department to open tomorrow before I can get a new one and keep testing. Could this be the culprit or am I chasing a red herring?
![[Linked Image]](https://j30.us/ubbthreads/ubbthreads.php/ubb/download/Number/1780/filename/photo%20(8).JPG)