Sounds like the tender has the wrong pickup arrangement compared to the engine.   Some engines will have pickup + on one side, - on the other. Sounds to me like you have inverted polarity at the tender.  But that would not explain the dead after 5 minutes unless the decoder did a reset.

Marc Fournier, Quebec 

Thanks Marc,

There's no decoder in it. I'm running it on DC until I convert to DCC.

Bernie

I would recheck the wheel sets on all the trucks also check to see if there isn't a loose wire between the tender and engine as it may be shorting on the frame someplace. The one set of wheels you reversed may have been the only one that was in the correct place and I would recheck all the wiring. Most engines come with a wire diagram to show you which wire goes where so check the box it came in and if you can't find that Drawing of the Engine and tender Break down. If it doesn't work after that call the manufacturer or the place you bought it and get a replacement. Also 1 last thing Check inside the tender: I have bought 2 engines in this past year that were called DC/DCC Ready & they said No Decoder installed. When I got Home they Both had The DCC Decoder installed & had I run them on straight DC it may have caused trouble or burned out the DCC decoder so check for the Decoder if you haven't already.

Dan