temperature displays

I was going to find you a part number for the transistor, but then I noticed the resistor above and to the left a bit.  Then I noticed the trace from the resistor to the microprocessor has heated up.  The microprocessor is probably toast.

If you look at all the "fingers" under the RHOS type that is most likely where the screen makes a connection with the board.  They use a "zebra" strip thats basically a conductive cushion to make the connection between screens and boards.  If you don't look at the little strip closely you would never guess that it is conductive.  This is also why if you don't put enough pressure on it the actual display doesn't work.  The only thing is is that I never saw a zebra strip in any of the pictures!

How are you burning these things up?

Wow, good eye.  I didn't scroll over and it was completely cut off my screen!

I think you can also see it in the first picture too, it's just really small and hard to make out.

tid=105885&KW=low+fuel

There is the op amp circuit that I am an idiot posted.

For such a low voltage you may need to modify the 10K pot on pin 3 of the op amp to include a 2nd resistor in series with the pot (creating a voltage divider and allowing you to focus the pot on a smaller voltage range).

I would also recomend getting a pot with as many turns as possible (>20).  That will allow you to dial in the voltage with more precision.

Why would the transistor need to be replaced?  I'm not familiar with the 2n2222 but I always thought itw as a fairly decent general purpose transistor (it seems to be the most common transistor used on internet diagrams).  If the 2n2222 doesn't work I know a 2n3904 will work.

The base resistor, R2, will have to be dropped quite a bit, as well, probably down to 470 ohms if I had to guess.