Doesn't sound like a great situation tbh! Though I'd be surprised if it was the HP pump, much more likely to be electrical in my opinion.
If you have a multimeter you can test sensors and stuff, especially the FRPS/FPR which would be my guess, look for Poodle's thread for info on testing.
If you have a multimeter you can test sensors and stuff, especially the FRPS/FPR which would be my guess, look for Poodle's thread for info on testing.