Evinrude 15hp 1978, ran good last year, I periodically would crank it up and it would run fine. The other day I cranked it up to check and make sure the water pump was working it wasnt. I let it run just a few mins and it died. It has no fire on the spark plugs, checked the voltage from the stator it had fire there but was very low volatage, and there was none past the power pack. Any suggestions before I go buy a new power pack?