Some may think this relevant to this thread, others may not.
Jet engines typically need a pump for them to run in a high altitude cruise.
Providing there is gravity feed (fuel tank above engine) the engine will run at low level without a pump.
The max altitude for running without a pump is type dependant.
So unless you want to land at a very high level please be assured you can relight a donk as you saunter into land if that donk has flamed out at height because it has no pump.