Guess my automotive naivete is showing (again) <img src="/forums/images/graemlins/confused.gif" alt="" />.

Don't worry. In some/most cars, it is drawn from the battery. Isuzu decided to switch it to alt power after startup. Most likely for a safety reason. If you crash your car bad enough, assumingly either the engine dies, or the front takes enough of a hit to disable the alt, then the fuel pump dies. If it was on battery power, it could keep pumping.

Michael