Its unlikely its the greasecar system because theres only one GC valve that the diesel passes through before returning to its normal course and Ive checked that valve and both the hose and the valve are very new and there doesnt appear to be a problem in that area, unless its very difficult to see.

I did use the method of pressurizing the tank. I did it through the return line as it was the only option. I was just hoping for annother entry other than the return valve as it made such a mess and is difficult to get at.

I guess Ill keep trying and see if I get it a 3rd time. 3s a lucku number eh?