I am sure this topic has been discussed but I have not found it in the search so here it is again, my apologies for redundancy. I have an 80s model Yanmar YSM 12. Been a great motor for the last two years, always cranked and ran like a dream. I had to re-thread the return line (small metal tube coming from the injector) because the hole in the filter housing striped. That done I re installed, bled the lines and she popped off today. Needless to say I was ecstatic until throttled her up and she became erratic and eventually dying out. She continues to start and will idle without trouble but as soon as I throttle up she revs, loses her momentum and dies again. I have bled the lines many times and have never had this problem before, like I said she ran like a champ. Have I missed something?