At the end of 2010's "Machete," director Robert Rodriguez (2011's "Spy Kids: All the Time in the World") promised in true grindhouse fashion that federal-agent-turned-off-the-grid-badass Machete Cortez (Danny Trejo) would ride again in "Machete Kills" and "Machete Kills Again." He fulfills the first half of this promise with ravenously untamed sequel "Machete Kills," a tongue-in-cheek exploitationer that manages to be batshit-crazier than the first, but only about half as diverting. In trying to one-up himself, Rodriguez has overstuffed his plot and bombarded his ensemble with a recognizable but underutilized cast. Amusing in pockets but not for the long haul, the film tries to be too much at once and ends up somehow being less than what one hopes and expects.

Machete has barely had any time to grieve the untimely demise of girlfriend Sartana (Jessica Alba) during a drug cartel standoff when he is called in for a meeting with U.S. President Ratchcock (Charlie Sheen, credited for the first time under birth name Carlos Estevez). With the promise of becoming an American citizen and getting his record expunged if he completes his mission, Machete agrees to travel to the U.S./Mexico border and take down two alleged bad guys: revolutionary-turned-madman Marcos Mendez (Demian Bichir), a cataclysmic bomb trigger strapped to his heart, and, later, billionaire arms dealer Voz (Mel Gibson), who is masterminding an even bigger plot of terror. If that weren't enough, he is forced to fend off a vengeance-seeking bordello madame (Sofía Vergara) and a forever-in-disguise chameleon (played at different points by Cuba Gooding Jr., Lady Gaga, Antonio Banderas and Walt Goggins) seeking the $20-million bounty placed on Machete's head. Add to the mix Blanca Vasquez (Amber Heard), a Texas beauty pageant contestant and appointed tough-talking handler to Machete, and the return of saucy taco-stand owner/freedom fighter Luz (Michelle Rodriguez).

The best scene in "Machete Kills" is its first, a so-goofy-it's-great pre-show trailer for "Machete Kills Again...in Space," paving the way for an intentionally shark-jumping final installment in a trilogy that began its unlikely existence as a fake preview during 2007's "Grindhouse." It looks wacky, stupid and auspicious all at once, but to get to it one will have to wade through this disjointed precursor. Kyle Ward's debut screenplay makes sure that virtually no one is safe from whirling helicopter blades or Swiss Army machetes, but the typhoon of blood and entrails defies its B-movie style with too many obvious CGI effects and a cloying feeling that Rodriguez is tossing in most of this over-the-top violence out of sheer obligation. It's also too convoluted for its own good, the viewer spending so much time trying to follow the ins and outs of the exposition-heavy narrative that one rarely can sit back and just enjoy the joyous inanity on display.

At sixty-nine years of age, Danny Trejo (2013's "Violet & Daisy") continues to define his own special brand of coolness, and he doesn't have to do much besides show up to achieve this. Anyone looking for levity in Machete as a character will not find it; his idea of grieving over Sartana is to nonchalantly say that he just lost his lady while showing no outward emotion, then going to town on a blonde chick forty-plus years his junior. As Luz, Michelle Rodriguez (2013's "Fast & Furious 6") is put on the sidelines too long, not showing up proper until almost the third act. Her sparring with Amber Heard (2011's "The Rum Diary"), especially feisty as Miss San Antonio, is a comically inspired highlight. In a sprawling cast where few performers receive more than glorified cameos, Sofía Vergara (2012's "The Three Stooges") shoots bullets from a her metal-plated breasts and vagina as the man-hating Madame Desdemona; Lady Gaga (in her first film) shows unsurprising flair as the Chameleon's sexiest guise, and Mel Gibson (2011's "The Beaver") does what he can with megalomaniac Voz. He's better than this one-note part calls for.

"Machete Kills" has its unashamedly graphic, wacky pleasures, but they come in spurts in between a lot of dead space that extends the running time to a rambling 107 minutes. It shouldn't have been a second over 89. More of the same is the name of Rodriguez's game here, but in his desire to one-up himself he has turned innocent, breezy sleaze into a trial of a trifle. The action is okay, but never genuinely involving. The death scenes are gruesome, but to what end? The characters are not nearly equal to what this cast deserves. It's all kind of just...there, despite the occasional acerbic throwaway line. If Machete knows the score, as the trailers continue to remind us, then he should be more aware than anybody that he just lost.