We have a caterpillar 315 DL. Lately the excavator has been having issues starting. The fuel rail pressure is only at 1500psi cranking and it needs starting fluid to turn on once it turns on the pressure is 5000+ we have checked the return line and it’s fine. It’s not pouring out diesel. We have checked the injector return and that’s OK. We unplugged the sensor on top of the high pressure pump I believe it’s a solenoid and it goes to zero psi while cranking so it makes us think that that’s not that I’m wondering what you think it might be. Once the excavator engine turns on without starting fluid it runs fine on throttle position 1-6 and then anything from 6 to 10 it just suddenly dies after running the machine for maybe 5-10 minutes.
Sounds like a bad injector