20A fuse at ignition switch missing

[kaliona]

1978 Mercruiser I6 165hp. I'm doing some work on my instrument panel. . tightening connections, cleaning terminals, and maybe changing some gauges when I noticed I don't have the 20A fuse that sits between the ammeter and the ignition switch (according to the shop manual wiring diagram). I bought this boat years ago used and the previous owner has done some strange things to the wiring so perhaps he took it off. I'm going to put the fuse back in, but just wondering what that fuse is protecting and also should I use 18ga or 16 ga wire for anything I change on the instrument panel.
Thanks

 

[Silvertip]

Need more info on exactly what you intend to change since we have no idea what the previous owner changed.

 

[kaliona]

Plan on just changing the hour meter since the current one runs and stops intermittently. All other gauges will remain. I'm just wondering if I should add that 20A fuse I'm missing that shows on the wiring diagram.

 

[StingrayMike]

Are you sure a fuse is supposed to go there? is there a spot for a fuse at the panel? Some diagrams show a fuse, but the location is somewhere along the line. Could that fuse actually be at the fuse block?

 

[kaliona]

This is the diagram I'm referring to. I don't think I'm reading it wrong. Looks to me like the fuse is between the ammeter and the ignition switch. View attachment Instrument wiring diagram.pdf

 

[StingrayMike]

You are correct, there should be a fuse inbetween the gauges. Could the PO moved that fuse out of the helm panel to an unused spot on the fuse block?
there should be other diagrams that show fuses holders in the helm and what not.
if you are ssure that the PO didnt move the fuse to another location, it couldnt hurt to put it back, even if he did, its just aan extra fuse.
Factory wiring size us "ok". It is safe and meets the minimun requirements, if you have the room and can do it, a larger gauge wire could only help. the diagram has wires 8-16. If it shows 16, use 14.14, use 12. 8 should be good for the current aapplication. You dont need to go overboard, but alittle more couldn't hurt.....
IMHO.

 

[kaliona]

I haven't poked around behind the panel that has the rocker switches that control my bilge, blower, navigation lights, anchor lights, etc. These are all fused switches. Is this the fuse block you're referring to? My original question was what does that 20A fuse protect. The way I read the diagram, it is protecting all my dash gauges (and everything downstream of the ignition switch including my fused rocker switches). Correct? Also, according to the diagram an Accessory Fused Panel should be fed directly from the ammeter. All switches and accessories have worked fine the way it is now for years so I might just leave well enough alone. Except I will put that 20A fuse where it should be.
Thanks for input Caravelle