Q: Car doesn't start but cranks

You mention "adding" gas to the tank. If the tank was run dry, the fuel pump could have been damaged and, in that scenario, yes the pump should be tested to see if that is the problem. If, by chance, the vehicle was idle and there was existing gas in the tank for months, you could have bad gas (even if you added fresh gas, it may not be sufficient). If this is not an issue, that is assuming that the fuel itself is fresh, if the starter motor is turning the engine over rapidly, at sufficient RPM, but the engine does not catch and run, the possible causes of a no start condition run the gamut from ignition to fuel, air induction, or mechanical faults. If you suspect fuel starvation, you can always try introducing starter fluid into the intake during cranking. If the engine starts under those circumstances, obviously there is a fault in the fuel supply system but that includes a lot of possibilities and not just the fuel pump. If the gas is good and the fuel system (pressure, supply, etc.) does work, and there is a spark, typically that means that the air fuel ratio of the mixture delivered to the cylinders is so far off the mixture won’t ignite. Such could be due to an air induction fault like a stuck idle air control valve or, again considering fuel, could be due to a failed temperature sensor that must be working properly to signal the PCM to enrich the mixture on cold start. Regardless of the underlying cause, if you request a no start diagnostic the responding certified mechanic will get the problem diagnosed and repaired for you. Please let us know if you have further concerns or questions as we are always here to help you.