1983 CJ8- I changed the engine to a 4.0 to have fuel injection and my 258 was knocking. I had a problem getting the engine to start , had spark, compression and 49 psi on the rail. When I choked off the return line to the tank and forced the pressure to 65 psi it would start and run fine. I have a manual ball valve inline after the fuel rail and regulator to make the Jeep run. Any ideas why this has to run that high a pressure to operate?