2004 Mercruiser 5.7 blowing ignition fuse

[graygoat98]

I have a 2004 Bayliner 225 it is blowing the 15amp ignition fuse randomly. Last time it happened I was shifting back to neutral. Now blows everytime I turn on ignition. It happened about 1 year ago but after hours of looking for short it quit blowing fuse. Now it is back. Any Ideas?

 

[Silvertip]

Re: 2004 Mercruiser 5.7 blowing ignition fuse

There is an obvious short somewhere in the igntion system. If you turn the key to RUN (not START) does the fuse blow, or does it blow only when the key is turned to START. These are two separate circuits. If it blows in the RUN position only, then the circuit between the switch and ignition system has a short, or if this is an electronic ignition system the box itself may be bad. Keep in mind that the instruments are powered by the RUN position of the switch so the instrument panel wiring may be at fault.

 

[graygoat98]

Re: 2004 Mercruiser 5.7 blowing ignition fuse

It blows only in run position. I can disconnect purple run wire and engine will turn over without blowing fuse. Was not sure if shift sensor would be causing random trouble.

 

[Don S]

Re: 2004 Mercruiser 5.7 blowing ignition fuse

Have you done any electrical work on the boat lately? Or maybe some mechanical work on the engine?

 

[NYBo]

Re: 2004 Mercruiser 5.7 blowing ignition fuse

Welcome to iboats!

It blows only in run position. I can disconnect purple run wire and engine will turn over without blowing fuse. Was not sure if shift sensor would be causing random trouble.

I think you've almost found the problem. Follow that wire (it goes to the gauges, right?) and find where it's shorting to a negative battery lead, which will probably be black. It may be right at one of the gauges: the mounting strap is usually connected to to the negative battery lead.