Engine starts fine and idles fine. Top end speed is only 25mph and had been 50 mph. I suspect an intermittant powerpack problem as some times it will accelerate with no problem, and other times, it won't plane off. <br /> How many power packs does the 91 Yamy 175 have? Where are they located and can I test them with an analoge ohm meter? What setting do I use on the Ohm meter. Are the power packs easy to replace and what is the cost? What would be the labor time that I could expect to have to pay if I took it to a shop? Will continuing to run the motor with a bad pack damage the engine? Sorry for so many questions.