United came out of their busy schedule of cup fixtures with a return to league action at Vale Park on Saturday afternoon.
And caretaker manager Gav Skelton, installed after the Wednesday departure of Steven Pressley, went with a 4-4-2 formation with Canice Carroll and Ryan Loft in for Jon Mellish and Jack Bridge.
It took just 21 seconds for the visitors to take the lead when Gethin Jones robbed possession on the halfway line. He strode forward and fed it inside to Olomola, who held the ball up before feeding Jones on the overlap. A low delivery found Loft unmarked and up in support inside the area and he executed the simple task of tapping it in from close range.
Vale almost responded immediately when a move through the centre saw Bennett call for it. The big striker got a volley on the pass but Collin was down smartly to parry it away.
Carlisle got forward again in what was a frantic start when McKirdy and Loft tried to find a way through on the left wing, and a hurried clearance sat up nicely for Mike Jones to strike. It was bouncing awkwardly and the scuffed attempt bobbled wide of the upright.
Back at the other end, and still with just seven minutes played, Jake Taylor suddenly had space after a tussle with Canice Carroll. His rasping drive crashed back off the post and was helped on its way by Mike Jones.
The Valiants pushed for an equaliser and a downward header from Amoo found Bennett, who had moved a yard off his marker as a corner delivery came in. Collin was excellent once again as he stayed big to make an instinctive point-blank save.
Things settled down as both teams defended well, but a break from Amoo for the hosts on 26 minutes saw him cross early as Bennett showed at the front stick. His header took a deflection, and the corner caused all kinds of problems as it pinged around inside the box. Taylor and Smith had swipes at it, but the blue shirts breathed easy as it was hooked high and out of the box.
Tackles flew in as the game developed a real edge, with Loft and Mike Jones giving everything as they closed players down, and a long period of stalemate brought another moment of frustration for Thomas as he tried to angle a run inside the left back. His shot from 19-yards was slowed down by Legge and Brown was able to gather it up.
The half ended with a run and wild shot from Montano, and with United holding onto their one-goal advantage with a determined display.
A slower start to the second period saw nothing of note created in either box, but a long throw from Iredale on 57 minutes was allowed to bounce before being dealt with. McKirdy and Olomola were interested but Legge intervened to put it behind.
The corner was only cleared as far as Carroll, who was on hand on the edge of the box, and he twisted his way past his man before he clipped a measured shot at the top corner. It had too much on it and it went over the bar.
It brought things to life and Taylor went on a run before letting fly for Vale. It took a deflection and trundled behind for a corner. That was cleared, but the home side were quickly back on the attack when Amoo rolled the ball down the line before showing again to deliver it into the mix. Gibbons flicked it on and Worrall finished it off with a sliding clipped effort.
The introduction of Jack Bridge for Olufela Olomola brought a change to a 4-3-3 formation for the away side, but United wasted a good opening when the subsitute spread the ball to McKirdy. He dropped a shoulder but his 20-yarder was always heading wide.
Carlisle thought they'd taken the lead on 72 minutes when Loft spun his man in midfield before sending Thomas away. The wide man beat his marker and drilled the ball at the top corner, forcing a fine save from Brown.
Midfielder Mike Jones screwed one over the bar moments later, when he got on the end of a clearance from a Webster pass, but Loft should have put his team back in front on 80 minutes when Thomas dumped Gibbons to the floor before putting it on a plate. The big striker pulled the trigger but he couldn't keep it down.
Vale had moments of their own, with wayward crosses being allowed to run free across the face of goal, but disaster struck on 83 minutes for United when a Gibbons cross somehow got past an attempted clearance from Webster. He completely missed it and another former Carlisle player, Mark Cullen, said thank you very much as he headed it into the waiting net.
The strike proved to be decisive as a good United away performance was ultimately made to count for nothing.
Port Vale - Worrall (60), Cullen (83)
Carlisle United - Loft (21 seconds)
Port Vale - Gibbons (75), Montano (88)
Carlisle United - Carroll (53), Loft (87)
Port Vale - Brown (gk), Gibbons, Joyce, Legge, Worrall (Browne 84), Montano, Smith, Taylor, Amoo, Burgess (Cullen 73), Bennett (Pope 57). Subs - Maddison (gk), Evans, Lloyd, Brisley.
Carlisle United - Collin (c) (gk), G Jones, Branthwaite, Webster, Iredale, Thomas, M Jones, Carroll (Sorensen 88), McKirdy, Olomola (Bridge 64), Loft. Subs - Gray (gk), Elliott, Mellish, Hayden, Knight-Percival.
Referee - Martin Coy
Assistant Referee 1 - Marvyn Amphlett
Assistant Referee 2 - Thomas Harty
Fourth Official - Richard Bartlett
Attendance - 4,783 (343 away fans)