Jim, I think you hit the nail on the head! I just spent a few hours in the garage swearing, err I mean working on the Trooper and I also think it is the alternator! After messing with a few things and changing the fuel filter, I went to pull it out of the garage and when I started it, the relay under the dash was clicking like crazy and no juice besides the 12 volts from the battery. When I rev it, it must just get the alternator excited enough to generate enough juice to make it charge. Probably a regulator problem, but since it is internally regulated, a new alternator is in order. Once the rpms drop, no more charge and the fuel pump kicks out. I guess I will track down a new alternator tomorrow. The little green wire also looks fine. I am surprized that the 12 volts from the battery will not sustain it longer. Kind of weird how Isuzu uses so many relays. I guess if they don't have the juice to hold them shut, they just click open and no more fuel. It really should come as no surprise that the alternator is dying, it has 312,000 miles, and I think it is the original!! I know it has not been replaced in at least the last 200k. Anything to look out for buying an alternator besides not buying one from autozone or checker?? Also, it happens cold or hot, and yes it is a 2.6.