OMC/ Volvo penta 3.0gs ignition fuse keeps blowing

[Hchang]

hi, i just inherited a 1997 four winn horizon with a omc 3.0 gs model number is 302CPLKD. I’m confused about it cause supposedly it’s a joint venture between OMC and volvo? Anyways the 15amp ignition fuse under the helm keeps blowing after i try cranking it to start. i read up on a couple forms similar to this and checked for burnt wires, anything that can short but can’t seem to find the problem.i even changed the key ignition to a new and still same results. i got tired of blowing 15amp fuses and decided to throw in a 30amp and it everything works. Well i haven’t taken it out to the waters yet but any ideas on what it can be?

 

[alldodge]

Welcome
Going to 30 is a big jump, does it blow with a 20 amp?

To much current can be caused by the ignition or alternator. There will be small wires connected to the Alt, disconnect only the small wires and see if the fuse does not blow

Also check resistance of the coil

 

[Scott Danforth]

If you didn't upgrade the wire in the ignition circuit, jumping from 15 amps to 30 just makes the wire the thing that will burn up next

 

[Lou C]

The fuse is sized to protect the wire, if the fuse blows the circuit is drawing too much amperage, therefore the fuse blows. You need to find out why. Check all connections in the ignition circuit for high resistance/oxidation/corrosion. You will need a wiring diagram for your model, start with the battery/starter including the engine ground cable, then follow it to the alternator, then to the big cannon plug. Pay particular attention to the battery cables, if there is any sign of green corrosion in the wiring going into the connector, replace the cables. If you have wingnuts holding the battery terminals to the battery, get rid of those, and use self-locking nuts, the wingnuts get loose and cause excessive resistance. I like Ancor marine battery cables, they cost more but you can buy them all made up to the length you need, and they will last longer than automotive cables in a marine environment. On my boat I use marine-grade battery clamps bolted to the cable terminals, these can be easily replaced if they start to get corroded or oxidized. I like these because you don't have to worry about the threaded post in the battery stripping out if using self-locking nuts.

 

[cyclops222]

New motor to you ?
Sounds like the wrong HV coil. Or even a removed BALLAST RESISTOR wire. Removed by a DIY idiot.

 

[Hchang]

thanks for the reply’s. Yeah i’m aware of the 30amp fuse and how it’s not rated for it. Only reason i did so was to see if it had a instant short as soon as i turn motor over or a amp draw exceeding the 15amp fuse. i double check the connections between the battery terminals/ starter and found that the ground battery wire that connect from the engine block to the battery was slightly loose. i tightened it and it has not blown a 15amp fuse yet. Could it had been that simple? but ill do the ohms test on the ignition coil as stated above just in case. i also tried the method of disconnecting small wires from the alternator and the fuse did not blow. i guess the only way is to take it out on the water and find out.

 

[Scott Danforth]

Could it had been that simple?

Yes