Roger. Mine has done this before, too (1988 w/2.6L). Check the connections on the alternator, plus the tension on the belt (if there is too much slack, the alt isn't producing current). If all appears well, then pull the fuel pump relay (in the fuse box over the front driver-side wheel well), switch it with the A/C relay. If the problem is corrected, then it was simply the relay--a $10 part at any auto parts store.

Here's the theory--Isuzu wired the truck such that the fuel pump is run off the battery at start-up, then switches to the alternator during operation. In theory, in a crash, the engine will stop, thus stopping the fuel pump from flooding the scene with fuel. That is what I heard/read somewhere long ago--so anyone who knows better, feel free to correct me.