Hi guys I'm new to this forum so please bear with me...My Merc 50 runs strong for 40 seconds on the stand then shuts down I had it to the local merc guru to ck it out and 150 bucks later he said it was running fine in his tank and for me it hasn't run one day on my boat or on the stand for 45 seconds since i got it back from him...so I guess I need some serious help from anyone willing to impart some knowledge upon me...could be fuel ....could be electrical....so thanx in advance for any help I will be getting from you guys...Al deep in the adirondacks