But senior executives at PetroChina have misgivings. Even before oil prices started tumbling in 2014, the company, like many in the industry, cut investment spending sharply. This year, PetroChina plans to cut it another 10 percent. A continuing anticorruption campaign has added to the chill on energy spending.

China is broadly reassessing its global investment strategy as the country faces new economic challenges at home and abroad. Rather than blindly spreading its wealth around the world, China is growing more sophisticated about its deal-making in an effort to protect its profits and to ensure the right mix.

The prospects for the Ecuador refinery project now look hazy.

The chief financial officer of PetroChina, Yu Yibo, said the company’s cuts would include refinery projects, but he would not discuss Ecuador specifically. Wu Enlai, the board member who is the company secretary, said PetroChina had not yet approved the project. “It is in the stage of feasibility study.”

Several Ecuadorean energy experts question the economic sense of the project. Ecuador, they say, cannot justify the refinery unless the country significantly increases production. For that to happen, it must drill deeper into the Amazon, an environmentally risky and expensive proposition that has been politically charged since the operations of Texaco and the state oil company caused widespread pollution in the 1970s and 1980s. “If there is no guarantee of more production, this refinery will be a white elephant,” said Mauricio Pozo Crespo, a former economy minister.

The uncertainty worries many in Ecuador.

“Correa says there is no limit to how much we can borrow from China,” said Mr. Acosta, the energy minister during the president’s first term. “But if the Chinese don’t put up the money, there will be no refinery. I have my doubts.”

So does Luis Kwong Li, one of a handful of Chinese-Ecuadorean restaurateurs in Manta.

When he and his Chinese-born parents heard about the refinery project in 2009, they closed their restaurant in Guayaquil and moved to Manta to open a new one. They thought the restaurant would cater to Chinese employees looking for dim sum. But by this spring, only two Chinese investors, who hoped to build a valve factory, had come for lunch.

“The president built up a lot of expectations,” said Mr. Kwong Li. “Maybe it will still happen, maybe in two years. There’s a big hope among the Ecuadorean people that the refinery will create business and jobs.”