Ignition? Wires heating up during engine operation

[Matts5150]

Find out which circuits are indeed drawing too much current / or over fused considering actual circuit load.

A digital multi meter (some good clamp on ammeters functions as a DVM, also) will detect a bad connection / bad wire when used to measure voltage drop.

PS: for a 10 amp circuit, you need a 16 gauge wire. For a 20, a 12 gauge wire.
a 20 amp fuse on an 18 gauge wire is an invitation for at the least some melted wire /melted connectors (as you see in the pics), or for a fire.

Either learn proper marine wiring techniques, or leave it to a professional.

Thanks for all the information. I have a pretty good judgment of wire gauging I could be off by a little but I would say it's roughly 16 to 18 gauge. I also forgot to mention each side of the blade fuse has a different gauge wire which I found was kind of odd when I say gauge one would be 18 the other would be 16 roughly. I'm guessing the thicker one is the feed which is the red with purple stripe wire full of the wires in that terminal block of four fuses have the same set up with one side of the blade fuse a thinner gauge wire. This is all from the factory and the manual States 20 amp fuses I'm going to try and find that and post here to show you this is a factory thing not something I did.

 

[ttmott]

Keep in mind that wire gauge doesn't necessarily determine fuse size in a DC circuit. Wire gauge is increased to minimize voltage drop over distances.

 

[Matts5150]

Find out which circuits are indeed drawing too much current / or over fused considering actual circuit load.

A digital multi meter (some good clamp on ammeters functions as a DVM, also) will detect a bad connection / bad wire when used to measure voltage drop.

PS: for a 10 amp circuit, you need a 16 gauge wire. For a 20, a 12 gauge wire.
a 20 amp fuse on an 18 gauge wire is an invitation for at the least some melted wire /melted connectors (as you see in the pics), or for a fire.

Either learn proper marine wiring techniques, or leave it to a professional.[/QUOTE

I looked up the parts diagram on mercruiser website using the exact serial number of my boat and when I looked at the fuse box that I'm having the issue with it shows they are placed with 20 amp fuses so my boat has the correct fuses installed. I guess you're wrong about the gauge wiring for 20 amp fuses even the wiring that goes down to the fuel pumps are no less then 18ga very thin wiring and it's all factory. And i know ga wire pretty well it's thinner then 14ga regular lamp cord. If you were correct then on my 50 amp breaker one of the wires leading out of there is also no less than 18 gauge wire... And that's a 50 amp breaker that is connected to.

 

[Matts5150]

Keep in mind that wire gauge doesn't necessarily determine fuse size in a DC circuit. Wire gauge is increased to minimize voltage drop over distances.

Sounds correct to me thanks for the heads up

 

[Matts5150]

I believe I fixed my issue as I no longer noticed the wires heating up what I did was replaced the starter with new OEM starter and solenoid and also replaced 90 amp fuse. I cleaned replaced all terminals that were corroded or that didn't look great. Even though the starter was working it still was 15 years old and I figured while I was down there might as well replace everything especially that it's an extreme difficult spot

For all of you that have the same boat Sea Ray 240 sundeck 2007 the starter was extremely difficult to get to but not impossible and I was able to do so without removing the exhaust manifold even though it would have made things easier if they weren't in the way. I had to squeeze myself in the back and lean over the riser so basically I was upside down for quite some time I had to pull out every once in awhile because I was getting dizzy LOL but was able to remove the two bolts and remove the wiring taking breaks in between but all in all it was well worth it I was able to clean everything out and replace starter and solenoid and 90 fuse. Mine look pretty rusted and corroded out so I'm glad I did the job so that next season I'll be good to go. Thanks everyone for all your help. I'll give it the full test next season to see if I still continue to blow fuses.