Tesla's Model 3 deliveries will disappoint again, according to one Wall Street firm.

KeyBanc Capital Markets reiterated its sector weight rating for Tesla shares, predicting the electric car maker will report weaker-than-expected financial results for its Model 3.

"We estimate Tesla will announce delivery of [about 5,000] Model 3s in 4Q sometime early next week, below the sell-side estimate but likely acceptable for the buyside," analyst Brad Erickson wrote in a note to clients Tuesday. "While it is likely to be a few quarters before the Company's true Model 3 gross margin judgment day arrives … we think the Model 3 margin ramp will disappoint and investors will have to acknowledge no [Model] S/X growth at some point, which is not reflected in the shares."

Tesla's stock traded down 1.6 percent midday Wednesday. Its shares are up 48.5 percent this year versus the S&P 500's 19.7 percent gain through Tuesday.

Erickson noted his conversations with sales representatives at 18 Tesla stores revealed Model 3 deliveries for the fourth quarter were pointing to lower than his estimate. As a result, the analyst lowered his fourth quarter Model 3 delivery forecast to 5,000 cars from 15,000 cars.

"It's definitely a supply issue at this point. Elon [Musk] has obviously been very candid through the quarter of being in production hell, having difficulties in getting all the stop gaps in the supply chain opened up," Erickson said on CNBC's "Power Lunch" Wednesday.

In the third quarter, Tesla delivered 26,150 total vehicles, but just 220 Model 3 cars. Wall Street analysts had expected overall production of 25,860, with 1,260 Model 3s.

"Given Model 3 gross margin will not really ramp up until probably the middle of 2018 given the production difficulties to date, we think it could take a few more quarters before the company is more harshly judged if gross margin proves disappointing," he wrote.

Tesla did not immediately respond to a request for comment.