2008 Mercury EFI 4 stroke Fuse Issue

Aluminumforever

Recruit
Joined
Mar 29, 2011
Messages
2
I put my boat in the water for the first time this year. The power trim worked fine when I initially put the boat in the water. After running it for approximately 30 minutes; the power trim on the controls quit working for no apparent reason. Completely dead. The power trim at the motor was dead as well. I ran the boat for approximately 1 hour after the trim quit working and the motor shut down completely while traveling at about 3000 RPMs. No click, nothing. I troubleshot it to the 20 AMP fuse for the power trim / master switch. Replaced the fuse and it started right up and the power trim worked. I ran the motor for approximately 30 more minutes getting back to the boat ramp. What would make this fuse blow? Could I have damaged anything else before this fuse blew?
 

sxmerc

Petty Officer 1st Class
Joined
Jul 13, 2010
Messages
247
Re: 2008 Mercury EFI 4 stroke Fuse Issue

Which engine is this? You neglected to include this info.
 

sxmerc

Petty Officer 1st Class
Joined
Jul 13, 2010
Messages
247
Re: 2008 Mercury EFI 4 stroke Fuse Issue

I know this doesn't sound like it makes any sense, but check the starter motor and battery cables inside the cowl for signs of heat damage. There have been a few instances where at certain RPM's engine harmonics and vibration have shorted inside the starter motor, and caused it to engage the flywheel while the engine was still running. First couple times this happened to the customer, all I could find was a blown fuse, and no reasons for which it happened. The third time it happened to him, the battery cables got so hot they set the sheathing on the cables on fire, and he wound up with a full on under cowl fire. It did alot of damage!! After consulting with Merc, they informed me that they had seen this happen to a few motors, and it happened to seemingly random engines. There is no telling which motors will be affected, as most are fine, and there have only been a "few" with this condition. They do however have an updated starter to replace the defective style, and will only replace starter motors on motors that have experienced this failure. On another note, I did get them to cover all the damage done by the fire on BOTH of the motors that I have worked on that have had this issue. My advice would be to look REAL closely at the starter and cables, and check for signs of heat damage. If you are at all convinced that there might be, get this thing to your local dealer, and get it checked by them. You do not want a under cowl fire. While this may not be your problem at all, it is a possibility, and I just thought the story sounded way to familiar to not mention it. Hope this helps out.
 
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