I live in Chandler AZ right up the road from picacho. Keep driving up I-10 till you get into Chandler. Chandler Blvd. Exit. There is a place called Cunningham (1230 South Akimel Lane. There number is 480-282-4000. Call them, they are open 24-7 and you'll see their sign as you drive up I-10. Hope this post isn't too late.
By the way the cheapest place in AZ for diesel is right up the road from you in Eloy. Its the Circle K truck stop. I-10 exit 203 at mile 204. I thinks its $1. 44 right now. Exit 200 has fuel at the same price at Love's.