i use ether ,it can cause problems.you need to install a lift pump.mine has a carquest electric fuel pump on it. it is installed between the fuel tank and filter.
While I am NOT suggesting a fuel pump will solve your problem. You may want to look at these posts, if you elect to go that route.
Your one thread indicated the injection pump might need repaired. I would call around on the costs to rebuild it. Also in the ctm125 manual URL posted in earlier thread it addresses how to remove/install the pump.
