2006+ T9.9GPLR Fuse keeps blowing

[clint_sands]

I operate a rental facility in Northern Illinois. I have (6) Yamaha T9.9GPLR for my pontoon boats. Two of the motors sporadically blow fuses while it is rented. I can not get it to blow for me. I have tried starting and starting the motor repeatedly while using the tilt as well. There seems to be no pattern as to when the fuses blow.

Anyone have any idea what could be causing this?

Thanks in advance,

Clint

[Sequoiha]

Ideally would be which fuse blows and is there anything in series with the same system.. the boat and the engine should be on seperate systems, if the engine main fuse is blowing it could be a ptt motor pulling too many amps, but it could also be a self inflicted wound if the customer (renter) is in the sand or mud, like trying to use it as an anchor at the beach..

[clint_sands]

It is the main motor fuse.

[TownsendsFJR1300]

In general, a blown fuse is usually from a curcuit, being shorted out to ground.

I would be looking where any wires pass thru the engine cowling, specifically near any metal parts. Look for any spots of dark arcing. You didn't mention turning the engine to the left or right, you may want to put it on muffs and try that as well. That's about the only thing differently your customers are doing vs you checking on dry dock..

Checking the control box as well may be needed, but I'd be leaning towards any moving parts.

Has ANY recent work been done to the boat/engine?

**Also, is it two separate motors on TWO different boats or both engines on the same boat?