I have a technical question about Back to The Future which contains many spoilers

[Hassled]

So - at the end of BTTF2, 1955, the DeLorean is caught in a lightning storm and goes to 1885. Marty (in 1955) finds where the Doc has left it (in 1885) and goes to rescue the Doc.

BUT that DeLorean is the DeLorean that features at the end of BTTF1, as in it has Mr Fusion power, you can use bananas/food waste to power it and it flies. The 1885 DeLorean is that one, not the original 1985 one.

So why then do they need to fanny around with a steam train to get it up to 88 miles an hour to get back to the future in 1885? Why don't they use waste food to power the flux capacitor?

Mr Fusion powers the flux capacitor, so they don't need 1.21 gigawatts or a lightning strike to time travel.

The car itself still requires fuel.

Just to mess with my head further, right at the end of BTTF3, the 1885 Doc manages to get to 1985 on the steam engine "powered by steam". No Mr Fusion, no Plutonium, no lightning, no nothing. And the steam engine flies.

No Mr Fusion, no Plutonium, no lightning, no nothing.

He's done something clever that you can't see.

:o

At the end of the first one when he picks them up in 1985 Martyr says after he's refuelled with food they don't have enough road to get it up to 88mph and the doc says where we're going we don't need roads so the food source is only the fuel it still needs to pick up speed to work. It doesn't work at the end of the third film although I can't remember why so they use the steam train to make the flux capacitor kick in.