A team spokesman said: "Although we had hoped to introduce PU2 this weekend, a quality issue means that this has now been delayed by one race".
For his part Vettel believes Ferrari's 2018 auto is not now "a true match" for Mercedes, despite having won the first race.
The delay, which also affects Mercedes customers Williams and Force India, would not affect performance in Montreal, the team said.
The plan for the works cars was to switch to the new specification for Canada and then use the original units again for a seventh time in Hungary, a track where ultimate power counts less than elsewhere. As with Schumacher before him, he looks to have mastered heavy braking and acceleration on the circuit's long straightaways that lead into tight chicanes.
Renault and Honda have confirmed updates to their engines for this weekend and Mercedes had planned to bring the next step in its development to Montreal.
"It's a great track and a real test for the driver and the vehicle".
"I can't wait to get to Canada as it is my favourite race of the year", commented Stroll, who was himself born in Montreal.
The video, published on Tuesday, June 5, pages Scuderia Ferrari, says: "We are ready to Montreal".
But others have also found the track to their liking including two of Hamilton's biggest challengers.
Notably, Mr. Hamilton performs well at the Canadian Grand Prix having won it 6X, and 1 more win and he will match Michael Schumacher's wins record there.
Sauber and Williams will continue to linger towards the back but have shown they can get drivers on the fringes of the top 10 when running well.
Southern Ontario last hosted the Grand Prix in 1977, when Bowmanville Ontario's Mosport Park was the site for the F1 auto race.
That emotionally charged weekend was capped off by a sixth win in Canada. Don't forget throughout 2018 GiveMeSport has joined up to the new F1 fantasy game with our own public league for you to test your wits against us! The Silver Arrows team principal Toto Wolff admitted they are pushing to bring as much performance as possible to stay ahead of their rivals.
Mercedes are now ahead of Ferrari and Red Bull Racing in both the Drivers' and Constructors' championships, but have faced a stiff challenge in all the races thus far.