No case against disgraced Firepower boss

The corporate regulator's evidence against former Firepower boss Tim Johnston has been deemed insufficient to launch legal action.

The corporate regulator's evidence against the former Firepower boss has been deemed insufficient. (AAP)

Investigations into the $100 million collapse of fuel-saving pill maker Firepower have failed to dig up enough evidence to warrant legal action.

Perth-based Firepower promoted unproven fuel-saving pills until it collapsed in 2008, leaving investors more than $100 million out of pocket.

Its disgraced boss, Tim Johnston, has been banned from managing a company for 20 years, but is believed to have squirrelled away millions of dollars offshore despite being declared bankrupt.

The corporate regulator on Friday said its brief of evidence against Tim Johnston and others at the company had been deemed insufficient by the Commonwealth Director of Public Prosecutions.

"The CDPP has recently informed ASIC that it is not satisfied there are reasonable prospects of a conviction," it said.

Liquidators wound up their investigation into Johnston's personal assets in 2012, due to mounting costs, meaning little has been recovered for investors who lost money in the company.