I have a Puch Odyessy Road Bike and I'm adjusting the front derailer. It's a suntour with stem mounted friction shifters. For some reason, when I pull down on the shifter to shift, it doesn't hold and the lever moves back to start position.

The rear derailer works great. If i pull the shifter down, it stays in place.

Any suggestions?

the side screw of the shifter was loose. this didn't let the shifter hold tension.

problem solved

good news

Yeah, my old stem shifters always did that - I had to constantly twist the little wing-nut to maintain friction.