Yamaha 50hp no revs under load

Hi guys, yesterday I went out on the water with boat with a Yamaha 50hp short shaft motor.All was going well for about 10min on the water, engine ran well at max revs and boat got on plane.Then it slowly started losing power like something that doesn't get fuel.I stoped to check fuel tank level, it was fine, I removed the engine cover to check if fuel gets to the carburators and it did.I pumped the bulb just to make sure and it was hard.While engine was running I removed the sparkplug caps one by one every time hearing a difference making me believe that all of the sparkplugs fired.After that I put it in neutral and reved it, revs went up as normal, engaged it in fwd but still it only ran at half the revs it used to.Please help!!!!!

Re: Yamaha 50hp no revs under load

Sounds like a fuel problem. Dirt in filter, weak fuel pump, stuck carb float, etc. Reving in neutral doesn't mean much, cause it don't take much gas to do that.

Re: Yamaha 50hp no revs under load

may have overheated or low on oil and safe mode was triggered.
Hard to tell what motor you are dealing with since you did not post the model #

Test the alarm system to make sure it works properly, giving an audible alarm and lights if you have that
You can check timing when running good and bad to see if the safe mode has retarded the timing