1999 Bayliner 3.0 Mercruiser – Keeps blowing ignition fuse – Help! Summer almost over.?

I have read so many different articles on this subject but, not sure how to specifically diagnose. Details of my issue are as follows: There is no circuit breaker or no inline fuse. The ignition fuse is under the dash. I have never had this happen before. Over 14 years enjoyment. This year, after only 2

I have read so many different articles on this subject but, not sure how to specifically diagnose. Details of my issue are as follows: There is no circuit breaker or no inline fuse. The ignition fuse is under the dash. I have never had this happen before. Over 14 years enjoyment. This year, after only 2 successful outing, initially, when the boat was idling it would not blow. I have moved around wires while idling to try to find a loose or questionable connection at dash and in engine compartment with no luck. When I took it to just over 25 mph is when it happened the first time. Engine cut off and no power to gauges. Blower and radio circuits still fine. Putting it in and out of neutral fine. After replacing fuse 3 times (first 2 blew out consecutively when I turned the key) it seemed to be fine. Start fine, idle fine, shake wires trying to find culprit nothing. Went out again yesterday and as soon as after I hit around 25 mph for a while the engine started to cut off (like before) and fuse went again. Replace the fuse 4 times and blows out consecutively. Have not gotten any further than that. One thing I noticed was that the battery console gauge was jumping around actively when the engine was cutting off. Also, during the last outing, when the first fuse was blown out it was just about melted (came out in 2 pieces).

Other answer:

Carlos:
Some more info … because posting character limit was reached… thx

The only significant thing that has been replaced in the boat was the alternator 2 years ago. Which still looks almost new. Battery cables, alternator wires etc look fine though. At this point I am tryin to figure out where I should be looking more closely and, what is the specific process for tracing a wire with a meter or anything else that makes sense. Although I am very handy and have had a good amount of experience with engine work, I have never done any electrical troubleshooting on engines. Thanks in advance for help!

I FOUND THE SHORT … WIRING BUNDLE ON TOP OF ENGINE HAD SNAKED TO THE BOTTOM OF THE WATER HEATER HOSE (What it was cable tied to). UGLY! THE WIRES HAD BEEN RUBBED RAW AND THEN SHORTED TOGETHER (8 of them).

leadpipe58:
Run a new brown wire from the ignition terminal on the switch to the positive side of the coil with a fuse in line. If it does not blow the fuse use that wire to run the engine.Finding a short can be almost imposable just replace the wire in question.Wish it were that easy in cars.
some ignition wires have a resistor in line to drop it down to 9 volts when running. you might add one in line as needed.
Harry Buttcrack:
I'd start by testing voltage at the battery. With the engine off, you should have 12.2 – 12.7 VDC. With the engine running at idle , you should show a reading of 13.5 – 14.1 VDC. As you increase the engine rpm, the voltage reading should rise slightly, but not above 14.5 VDC. A higher reading as you increase rpms would indicate a failing regulator circuit in the alternator- this is worth a look.
glancy@rogers.com:
check with in your switch system there may be some bear wires with in the system good luck