also check your selenoid, or start it with a spoon or a copper object between the red and the black cable on the Selenoid, don't let it ark lol I melted a pair of scissors. I haven't had a problem since a while since I started leaving my battery on the charger and the wire mod and the cleaning of the battery terminals and the selenoid... Try to start them with a car battery if it starts your batteries might be fooked. lol I'm not a mechanic or pro but I think your problems are due to battery and/or Temperature or Idle Adjustment related since both of them fail to start and both of them start at the same time. BTW did you fuel them from the Same gas container? I used to get a lot of ****** Gas in California, who knows you might have some bad gas/water in your tanks... don't sell your babies man keep those or I will come down there and burn all your rubber in 12 hours on both of them! lol good luck!