actually, diesel doesn't explode with electricity. diesel trucks use glow plugs to start off with and after that, they use extremely high pressure to keep the explosions going. but glow plugs are just hot pieces of metal. diesel right now is perfectly fine the way it is.
and anyways even gasoline isnt ignited with electricity, you CAN have powered wires submerged in gasoline without combustion, its the VAPORS (as lockheedmartin said) that ignite AND the spark plugs make a SPARK which is NOT just electricity, as the SPARK generates heat and pressure