I have 2004 Powerclean 5.9 with a Nissan motor - unit kept shutting down after a few seconds after starting. At times it would run longer, I thought it was the electric fuel pump so I switched it. But I notice still there is no fuel coming out of the return lines back to the tank. So i checked and there is no fuel coming out of the fuel regulator. Where can I find a regulator for this engine? It is a Zenith fuel injection. Is there an after market or car substitute?