SEATTLE — Voters approved a constitutional amendment that places new limits on state debt and rejected another that would allow state research universities to invest reserve funds in private companies or stocks.

Voters gave a thumbs down in two nonbinding advisory votes on state laws passed earlier this year. One law extended a petroleum tax that goes into the state pollution-liability-insurance trust account, and another removed a tax break for certain large banks.

The constitutional amendment on debt would, over time, restrict how much debt the state can take on.

Currently, the constitution says principal and interest payments on debt cannot exceed 9 percent of tax collections going into the general fund, averaged over three years. The proposed limit, beginning July 2014, is 8.5 percent of the average over the previous six years, falling in 2034 to 8 percent.

The measure dealing with research universities would affect only the University of Washington and Washington State University. It would allow investment of public monies of those institutions in private stocks and bonds. The Legislature would specify which funds of the universities could be invested and how.

The advisory measures gave voters a chance to weigh in on two laws approved by lawmakers, but the results aren’t binding.