Originally Posted by dP3NGU1N

Isn't the pump at the bottom of the tank anyway? The head of the fuel pump assembly has springs so that when you secure it, it provides constant pressure holding the rest of the assembly at the bottom of the tank. I think the most dangerous thing that might occur when the head breaks is that the assembly is free floating around the tank. Considering the fuel level sensor is also attached to that assembly, it will lead to inaccurate fuel level readings to boot.

Also, seems unlikely that it's the fuel pump if the car is running. I think the fuel pump is running at a constant cycle, more or less throttle has nothing to do with the fuel pump (someone fact check me, pretty sure that's how it work). There should be a separate mechanism that adjusts fuel input into the engine.

OPs issue still sounds like a clutch issue to me. The mechanic should warranty his work considering he did not solve the original issue. Hopefully you told him about the issue and didn't just pop by asking him to change your clutch without context. A good mechanic would have taken it for a test drive to ensure that the issue is fixed before returning your car.