So…many…quotes…
Ash: “We can take these Deadites, we can take 'em… with science.”
Ash: “It’s a trick. Get an axe.”
Ash: “See this? This is my boom stick!”
King Arthur: “Are all men from the future loud mouth braggarts?”
Ash: “Nope, just me baby. Just me.”
And that’s just a small selection from one movie
Army of Darkness: Dude with a chainsaw hand and a shotgun is sucked into a vortex back to the 1300s to do battle with the undead. It’s sci-fi because of the time travel. Plus undead. I prefer Evil Dead 2 but that falls squarely into the horror genre I guess.
The Adventures of Brisco County Jr.: Steampunk? Remember Wild Wild West? This was that but with Bruce Campbell. Was the movie just the beginning of the series?
Bubba Ho-Tep: The real Elvis battles a mummy in a nursing home with a black JFK! How could that not be Sci-Fi? 
He was also in Darkman (which would make another great Arc) and looking into it I haven’t seen Alien Apocalypse, Timequest or Man With The Screaming Brain.