I had an amazingly similar scenario happen this winter that may(or may not) be useful. My sisters 2000 Jeep Grand Cherokee 4.0 reportedly would crank but not start. I arrived ready to change a CPS as that's what my reading of various Jeep forums indicated as a likely culprit. BUT I stumbled on one thread that suggested a dying but not yet dead battery could cause this also due to the ECU not "liking" what is was seeing voltage or amperage wise from the battery. I arrived onsite and sure enough she cranked ok but wouldn't catch. I "feathered" the gas while cranking and she started and stayed running as long as I "feathered" the gas, but died as soon as I took my foot off gas...weird but it didn't strike me as a CPS issue. Battery looked old, I removed it and drove it to Advanced Auto for a test and they said "its bad must replace". Not even the normal, "charge and re-test", it had a fully dead cell. I bought a new battery plunked her in and Walla! Started and ran immediately with no foot on gas. No issues since, none. ECU did not "like" something about what it was getting/seeing from battery so it wouldn't run/start. I am sure some engineer type out there may have a better understanding of the why, I do not. It just worked.

First question would be "Why did they quit driving the Trooper ?" Isuzus were pretty reliable. It sure sounds like it is not getting fuel. Does the fuel pump run ?

E10 fuel is not very stable, but I have had the same gas in my Honda since October and it still starts fine.

Greg

Is this engine carbureted and how long has it been idle?

You may be looking at old gas in either case.

A carburetor unit may have dried out enough to gel up the jets or needle seat where a fuel injected engine may eventually pass enough pressurized fuel to clear itself unless it's all jelly from the tank forward.

Running ten seconds on spray is quite awhile unless you doused a bucket full in there some how? It does prove that the other things are working though.

Phil