stopped by the machine today. didnt have a lot of time but checked a few things. Fuel pressure at secondary fuel filter. Engine idling 110psi. Book calls for approx 85 psi. high idle 150 Psi.(book 95 - 105psi) remove fuel return hose no return fuel at high or low rpm. removed check valve where fuel exits head... just a small bit of sludge no fuel. seems we have a blockage of some kind in there.