The Senate Commerce Committee kept the federal no-fault auto insurance bill alive yesterday but postponed final action for at least a month by ordering a financial study of the Michigan and Colorado state no-fault programs.

The study, to be conducted by independent actuaries chosen by the Department of Transportation, is to be completed by April 4.

The Commerce Committee agreed to meet April 6 to consider approving the bill, which in effect requires every state to adopt a no-fault auto insurance system based on federal guidelines.

Under the no-fault system, a person hurt in an auto accident would be paid up to $100,000 medical expenses plus compensation for lost salary by his own insurance company, without having to sue the other driver. The inpured person or his or her family could sue only if there is permanent injury, disfigurement, or death.

Proponents say the bill would save hundreds of million of dollars in lawyer fees. However, the American Trial Lawyers Association, whose members include most lawyers trying auto-injury suits, opposes the no-fault system as robbing persons the no-fault to sue.

Sen. Warren G. Magnuson (D-Wash.), longtime sponsor of the bill, appears to have the votes to get it out of committee, but opponents led by Ernest F. Hollings (D-S.C.) have stalled a vote and demanded new studies of existing state programs. A Hollings proposal for three- to six-month study could have killed the bill by delaying Senate consideration until the very end of the session or beyond, leaving no time for House action, but Hollings agreed yesterday to a compromise calling for only a one-month study.