The Motormen have taken just two points from the last 12 available, a slump which began with defeat at high-flying Burton, a game that could have seen Vauxhall go top.
Last Friday's game in North Wales got off to a fiery start when Wayne McDermott was booked for a heavy challenge on Marc Limbert. Colwyn Bay created most of the best opportunities and should have gone ahead from a corner kick but Chris Holmes produced a spectacular double save.
First he blocked from Jason Jones before denying Dean Williams on the goal-line.
But Holmes' best was yet to come as he palmed away a Deniol Graham effort from point-blank range and it's doubtful there will be a better save at this level all season.
In fact, the Motormen's best chance was from a 35-yard opportunist effort from Nicky Young but keeper Paul Smith tracked back to his line for an easy catch.
The home pressure finally paid off a minute before the break as Danny Barton nodded home a free header from Limbert's corner kick.
Colwyn Bay kept up the pressure in the second half and nearly went two up when Brad Cullen misjudged a back header on the wet surface which left Holmes scrambling.
Vauxhall had rare surges forward and McDermott almost drew them level, but his effort was tipped over the bar by Smith.
It was only with the introduction of Robbie Lawton 10 minutes from time that the Motormen started to threaten.
It was Vauxhall's other substitute, Jon Stanhope, who had the last chance to level the scores but he fired over from close range after latching on to McDermott's through-ball.
Manager Alvin McDonald said: 'I'm disappointed. The effort and commitment was there but there was a lack of quality.'
Vauxhall: Holmes, Rigby (Lawton 80), Thompson, Brazier, Haddrell, Lynch, Croxton (Stanhope 70), Cullen, Fearns, Young, McDermott.