I have a 2012 mcs and when I first got it it ran good for a while but then it would starting stalling and dying while driving around town. It stalls out almost like it’s running out off gas. After it dies I can restart the car and it’ll run fine for another few minutes before acting up again. Eventually some codes will pop up saying hpfp plausibility and fuel pressure sensor plausibility. I changed the low pressure pump because the old one had broke where the bottom and top connect. I also replaced the fuel filter cuz the car was new to me and has 124000 miles. After replacing those the car ran great for a couple months but now the same problem is happing again. I now suspect the hpfp is going bad is there any way to test this part?

 

So I codes went away and right now I have the obd scanner hooked up reading the hpfp and the set point value hovers around 5.12 mpa and the pressure reads between 5.06 to 5.21 mpa