2004 Mercruiser Ignition fuse blowing

[jackl2000]

I have a 2004 Mercruiser 4.3 carbed engine in a sea ray 185 boat. Boat starts with no problem, engine runs smooth and in about 5 minutes, the 15 Amp ignition fuse blows. Put in a new fuse and turn key and fuse blows almost right away. Starter engages and then pops fuse. To test I have disconnected alternator, fuel pump, auto choke and + side of coil. Same issue. Turn key and it blows. I checked all exposed wiring that I can see and it all seems OK. Wires to solenoid are OK as far as I can tell. I am stumped. Could it be ignition module?

 

[alldodge]

Your saying ignition fuse, and this would be the one that is inline with the Red/Purple wire coming from the motor to key switch. If it is the ignition fuse, then it is normally a 20 amp.

Is this a TKS carb motor?

 

[jackl2000]

It is definitely a 15 amp fuse. 15 at the fuse block and 15 in the manual. I tried a 20 and it still blew instantly as well. It is a TKS Carbed motor.

 

[alldodge]

Disconnect the TKS module, ignition module and oil pressure switch. If it still blows the fuse then the wire has a short

 

[wingless]

Welcome to the forum.

A good first step would be to disassemble, inspect, clean and reassemble all the power connections, from the battery, to the engine, back to the battery.

Start w/ disconnecting the battery negative terminals for safety.

Then disassemble each bolted / screwed connection, one-by-one so that the engine gets the full available voltage.

When bad connections exist and the load remains constant, then extra current is drawn, potentially causing the fuse to pop.

 

[jackl2000]

Thanks wingless. I did disconnect battery wires, cleaned and reassembled. I did not remove others as connections were tight and no frayed or loose wires.

 

[jackl2000]

Anyone else with any thoughts on this?