Corrected entry: Doc Brown can build a time machine but is unable to figure out how to build a still to extract pure ethanol from Whisky in order to use as fuel for the DeLorean. He stated to Clara that he is a "student of all science" so this should include chemistry. Chemists know how to build a still. Doc, however, tried to fuel the car with strong Whisky without distilling it.
Correction: They did not have time to build anything, they were in a hurry to leave before Doc gets killed.
Correction: He would with no problem be able to get that thing to run on ethanol, just a different air fuel ratio bigger injectors so just make bigger holes in the ones you have. Just to run it one time would be no problem.
Correction: He needed a quick solution and thought the whiskey would work. Apparently his expertise does not include the workings of internal combustion engines or he never would have tried it. Pure ethanol would also probably not have worked in the DeLorean.
BocaDavie ★