Verstappen was forced out of the Australian Grand Prix on Sunday with 20 laps remaining due to a fuel system issue, costing him a likely second-place finish.
Verstappen also failed to finish the season opener in Bahrain last month due to a separate fuel pump problem, causing him to lose significant ground in the early title battle.
The Dutchman lies sixth in the standings with 25 points – all picked up with victory in Saudi Arabia - and is 46 points off runaway drivers' championship leader Charles Leclerc.
Verstappen called the issues "unacceptable" after the race, and later explained to the written media in Melbourne that Red Bull had a "lot of things to work on".
"First I'll go home, I'll talk to the team also when I'm back at home," Verstappen said. "We'll try and forget today and wake up tomorrow and focus again on the coming races.
"But also, it doesn't look like there's a clear fix. So we need to work hard to try and improve our reliability."
Verstappen had managed to battle Leclerc closely in both Bahrain and Saudi Arabia, but struggled to put up any kind of fight to the Ferrari driver through the Australia weekend.
Leclerc took pole position by almost three tenths of a second on Saturday at Albert Park, and controlled proceedings at the front despite two safety car restarts. He ultimately finished the race 20 seconds clear of Sergio Perez, who picked up second place for Red Bull after Verstappen's DNF.
Verstappen explained that he had struggled throughout the weekend with the balance on his Red Bull RB18 car, making it hard to get close to Leclerc.
"Balance wise, I'm struggling so much, it's really hit and miss," Verstappen said. "And in the race we had terrible tyre deg. So you can see we're definitely not in the right window.
"I mean, it's still a second place. But if you want to fight for the title, we need to be ahead of Ferrari, and they are definitely on top of a lot of things much better than us."
Red Bull F1 boss Christian Horner said after the race the team was "definitely out of the window" to battle Ferrari, putting the balance issues down to misjudging the track conditions and the tyre demands.
"What we saw on Friday was we thought the race was going to be rear limited," Horner said.
"We could see quite a lot of graining on rear tyres, and I think a combination of perhaps a surface rubbering in and particularly the temperature today, it then was almost an inverse problem and having tried to counter the issues that we expected from Friday, we ended up with a car that was very front limited.
"That is why I believe we were out of the balance window with the cars. So that's why we had a lot of graining, particularly on the medium tyre.
"On the hard tyre, it was actually not too bad. We never got to see Max's ultimate pace."
