Hey everyone - I'm hoping you folks can help me diagnose the problem that's been plaguing my 2009 250 GTS super ie for the last few months now. My suspicion is that the fuel pump is failing, but it doesn't really fit the exact profile. Originally noticed the issue at freeway speed after about 10 mins where the RPMs dropped off suddenly and the scooter started to hesitate and lurch. Letting off the throttle to keep it rolling at about 50-60 km/h worked, but it would not power back up until the bike was shut down and had cooled off. That happened a few times, but never had any issues if I kept it at or under 90 km/h around town and stayed off the freeway. My local Vespa dealer couldn't diagnose the problem. A couple of days ago I decided to take a quick check on the freeway to see if it was still happening and it bogged down almost immediately upon hitting highway speeds, and now, it's happening full-time and at much lower speeds. If I'm on level roads and don't accelerate hard, it works fine - try to accelerate quickly or climb a hill and it bogs down and nearly dies. It's not stalling, just won't allow me to twist the throttle beyond maybe halfway or it starts to lurch.
Sound like a fuel pump issue or any other ideas? Air filters have been changed and like I said, a qualified Vespa mechanic seems stumped. The fuel pump was replaced years ago in the recall. Any suggestions greatly appreciated.