Having tapped the equity market eight times for capital over the past seven years to fund Tesla Inc.'s growth—and cover its losses—Elon Musk is turning to the bond market.

Needing cash to finance his audacious bet on the mass production of a more affordable electric car, the Model 3, Musk plans to sell $1.5 billion of eight-year bonds. Tesla officials are meeting with investors across the U.S. this week to drum up demand. The debt sale will test Musk's ability replicate the fervent following he's built among stock investors, who've bought into his vision of a clean-energy future and pushed the shares up 67% this year.

While bond markets have been running at historically frothy levels, Tesla is asking potential noteholders to overlook the company's negative cash flow and its repeated trips to capital markets to bolster its balance sheet.