Your questions are a bit confusing. I think it is from mixed knowledge of our systems.
You have two fuel pumps. The fuel transfer pump, which is a Carter 12v weenie. We call that the LP for "lift pump". It supplies 8-15psi fuel to the other pump.
The other pump is a gear driven and electronically controlled INJECTION PUMP. This is the VP44 and makes upwards of 16,000 psi to fire the mechanical injectors.
Now to your concerns. They might find a bad LP if they lose prime in the system and can't get it back. Otherwise you can usually drive forever on a bad LP-until it ruins your VP44. That's why we all have FP gauges.
If the VP44 starts going out, you'll have serious drivability issues and maybe codes set in the computer.
HTH, and FIND a good stealer, there are a few out there.