I have a Merc 40 electric start and I have started having problems with the 20 amp fuse blowing? What happens is I am motoring down the lake and come to a stop I think I want to staop and I pull that control handle back and shut her down Fish for awhile and then go to start it back up to move BANG No power i have blown the 20 amo fuse .... Repace it an now I'm in. Can any one tell me what is making this happen

Year 1995

Make Merc

HP 40 Elect

Please help