Ignition fuse blowing - 2003 Searay 176 w Mercruiser 3.0

redfiveshoe

Cadet
Joined
Jun 14, 2009
Messages
16
Any help that anyone could offer would be appreciated. I was on the lake last night when after about 20 minutes the boat shut off. I turned the key to crank and got nothing. Found out that the ignition fuse was blown. Luckily I had extra fuses. I replaced the 15 amp fuse and turned the key to crank and it immediately blew the new fuse. I went through 4 fuses. I finally put in a 20 amp fuse and made it back to the dock.
The manual and the fuse block call for a 15. The temp gauge was recently replaced and I thought that may be the problem, but everything looked good there. So next I went to the alternator to check the purple wire and found that the bundle of wires that contained the purple alternated wire, the thermostat wire, and others have been sitting directly on top of the engine block and have melted to the block. I assume that this is my problem, right? When the block heats up it heats up the wires and blows the ignition fuse.
Two questions:
1. Is this most likely the problem?
2. Is this an easy fix? Could I just splice the damaged portion of the wires and reroute them so that they don't touch the block?

Couldn't get picture to attach.

Thanks for the help.
 

dannys2004glastron175mx

Petty Officer 1st Class
Joined
Jan 15, 2014
Messages
307
Re: Ignition fuse blowing - 2003 Searay 176 w Mercruiser 3.0

that's the first place to start the purple wire is connected to your ignition fuse

yes you can fix them jest get your self some shrink tube and some silver solder
 
Last edited:

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: Ignition fuse blowing - 2003 Searay 176 w Mercruiser 3.0

the motor runs at 145 Deg. not hot enough to melt insulation .Manifold is water cooled, again not hot enough to melt insulation.
The hottest spot is the exaust port for #1 cylinder and there should not be any wire bundels there either.
If the block is that hot ,you have bigger issues than melted wire.
 

redfiveshoe

Cadet
Joined
Jun 14, 2009
Messages
16
Re: Ignition fuse blowing - 2003 Searay 176 w Mercruiser 3.0

So good news. I spliced the wires that were melted and lake tested it this weekend and everything seems to be running fine.
I am concerned however about BT Doctur's comment about the manifold getting too hot. While on the lake , i took a temp gun and shot different parts of the motor. I got 170-180 everywhere except for the exhaust manifold. It was 200-205 up front and 195-200 near the back. Should i be concerned about this?
The boat seems to run around 175 anyway, according to the gauge. I recently had alot replaced thinking that it was running too hot. The thermostat, gauge, water recirulation pump, are all new. I also had it checked for any leaks and everything was good. The impeller has less than 30 hours on it (1.5 years) and the boat holds steady at 175, it doesn't rise at higher rpms. If it was the impeller, wouldnt the temp be rising at higher rpms?

Is the motor temp a problem? Manifold temp a problem? IF so, what could it be?
 
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