All I could find
Previously, when running on the regular fuel system, the motor really struggled to idle and the MIL light would flash. Nowhere near as dramatic running IP from jerry can. No MIL light and it did eventually settle into an idle.
Once idling I removed the radiator cap looking for evidence of a blown head gasket. As I understand it , the thermostat needs to be open for air pressure to move from the block to the radiator. Had to stop then to get helper home before dark.
Ok Rick, I got a pic of some substance from inside the tank itself, straight below the pick up entry. Camera software playing up so lousy details. For all I know, it's just the 1/4 inch remains of black beetle and not at all related. Still have half a tank of diesel left and other than the previous find, it all looks good in there. Even drew off half a liter to let stand in a tall glass bottle. Unless water/diesel separation is best left for over night, that's looking good too.
Blew out the lines and then packed up. Severe thunderstorm missed us, but they're predicting rain until the 14th. Surely there'll be an opportunity to take this further before then.
Still don't feel any closer to solving this, but I'm done for now. Thanks again, Roy