Quantum chiefs announced at the Abu Dhabi Grand Prix that they had completed their part of an arrangement to purchase a 35 per cent stake in Lotus, with the matter only needing monies to be transferred to Lotus' bank account.
It is understood that those transfers have not been completed yet, despite hopes that matters would get finalised last week.
Although Lotus is still hanging on for Quantum money, Lopez made it clear on Friday that time was running out before it considers a different path for its future.
Speaking to AUTOSPORT about the Quantum situation in the wake of the announcement in Abu Dhabi, Lopez said: "It was their own initiative to announce that the deal was done. It isn't.
"We have always said that if we want to push we have other options. It has got to be the right partnership. That one seemed like the right one, but whether it is going to happen or not, I don't know."
Lopez insisted that Lotus had not yet given up on the Quantum deal being finalised, but equally admitted it could not just sit back and give the investors forever to get things sorted.
"It needs to happen eventually," he said. "If it doesn't? Well...right now we are just running things as they are for ourselves, and then we will decide [what to do]. But we are for sure not going to give it forever."
When asked how long the team could wait, and if it was true that the team had set an internal deadline of today for Quantum to get it matters in order, Lopez replied: "All I can say is it will not be much longer."
Although the financial boost that would be delivered from the Quantum deal would be a big boost to Lotus, Lopez insisted that the team's future was not dependent on it happening - and that it did not have to seek a fallback option.
"We don't need to [find other investors] if we don't want to," he said.