Hmm, you didn't the say the model/make pickup, I assume Detroit Iron. Ford autos, such as my 89 Probe, have a fuel cutoff device located inside the carpet covering in trunk (obviously someplace else in your pickup, if you have such a safety cutoff), rather hidden if you haven't read the manual, that went bad on me & would cutoff fuel pump when it should not. It has a sensing mechanism that if the car receives excessive G-forces, basically from an impact, it shuts fuel pump off as a safety device. It did not exhibit your specific behavior or cutting off after 30 seconds of running. But, if your pickup has such a sensor, it is easily checked. Mine had a button to reset it.