Pep Guardiola’s side again looked sluggish going forward, and their lack of cutting edge proved costly as they had 26 shots but only managed to get seven on target.
West Brom goalkeeper Sam Johnstone made vital stoppage-time saves from Gundogan and Raheem Sterling.
The result leaves City with 20 points from 12 games, having scored only 18 league goals this campaign, a far cry from their usual free-flowing best.
Guardiola’s side have been trying to play catch-up all season, having started the campaign late due to their Champions League commitments in August, and Gundogan suggested the lack of a break was part of the problem.
“It’s nearly impossible to have just one team that’s on top and dominating anything, especially with the schedule coming up,” the Germany international said.
“All teams in Europe are struggling to win games in a row. But we have responsibilities and we should win these kinds of games, especially at home.
“We are human beings, not machines, we struggle as well. It is not going to get easier in the next few weeks.”
Gundogan opened the scoring after half an hour with what was City’s first clear chance from open play, but West Brom levelled two minutes before the break when Ruben Dias inadvertently diverted Semi Ajayi’s shot past Ederson.
It was the first goal City had conceded in 608 minutes in all competitions, and one that proved costly as Johnstone frustrated them late on.
“We should have won that game but we can’t change that now,” Gundogan added. “We can do better but it was not meant to be.
“We can complain but we cannot change it and must accept it. We have to look forward. We deserved better, we had the chances. I don’t know what to say, it’s disappointing to get one point. We must win these kinds of games.”