Code P1023 and random misfires for months. Long cranks to start for months if not years. Replaced gas cap and monitoring but no improvement.

This morning things got worse and now I also have P01026. Very rough running and no power, although able to continue to work even up to 70 mph. Previously checked fuel pressure with diagnostic tool and had 40,000 mbar setting and actual, higher with throttle application. Now I've got only 5,000 mbar actual on both fuel pressure and rail pressure, but SET pressure shows 0.

I'm pretty sure the high pressure fuel pump is not working, but it is strange that setting is zero. Is there some chance a sensor has gone out causing HPFP to not run. Fuel pump relay?

Thanks in advance for any suggestions.

 

Don’t forget the fuel filter.

 

It was indeed the high pressure fuel pump-changed out and everything is good!