Yanmar 6BY High rail pressure

[Fletch97]

Hello all,

Struggling with an issue on a Yanmar 6BY. Can drive upto around 3600 RPM with no issues but as soon as it gets around 3700 or above the check engine light comes on and goes into limp mode. Can be reset again when the engine goes off and on. The fault on my fault reader is saying high rail pressure. I have replaced the rail pressure sensor, LP pump, Most of the wiring looms, Rail pressure regulator and HP pump volume regulator but still getting the same issues. Any help or pointing me in the right direction would be much appreciated.