Starter issue? 3.0 Mercruiser.

[rpinson81]

Boat started up and ran fine for a quick 5 minute trip, 30-45 minutes later completely dead when the key is turned. No gauges, doesn't even attempt to crank, but the trim still works.

I've read through a bunch of different threads on similar issues and I think I've got it narrowed down a bit, but hoping for some confirmation. Battery tests fine, boat is in neutral, no issue with safety switch.

I ran a wire from the battery to the ignition switch and got power to the gauges and can also hear the starter clicking, but still no attempt to crank.

I'm down to either the 90 amp fuse on the starter or the slave solenoid, based on my limited knowledge and testing. Any ideas as to whether it is more likely to be one of those than the other based on what happened with the hot wire? Should I just replace both and also, is there anything else I could be missing? I hate throwing parts at it, but nobody in my area can even think about looking at it for weeks, if they want to do it at all. Really need it running in the next few days if possible at all.

Thanks guys.

 

[alldodge]

You need a voltmeter, can pick up a cheap one at wally world or other

Measure voltage on the red/purple wire at the key switch.
If no voltage look for 20 amp fuse by following wire back

If 12V is found, turn key to ON and verify you get 12V on purple wire
If no 12V replace switch
If 12V is there did gauges start working?

If 12V is on purple wire and gauges work, turn key to start and measure 12V on yellow/redwire
If no 12V replace switch
If 12V is there, go to slave solenoid

Measure voltage on yellow/red small wire on slave solenoid when key is turn to start
If 12V is not seen, then a bad connection or wire from key to slave
If 12V is seen, use a larger jumper wire and jump across the 2 large terminals on top of slave solenoid. When terminals are crossed the start should engage

 

[rpinson81]

You need a voltmeter, can pick up a cheap one at wally world or other

Measure voltage on the red/purple wire at the key switch.
If no voltage look for 20 amp fuse by following wire back

If 12V is found, turn key to ON and verify you get 12V on purple wire
If no 12V replace switch
If 12V is there did gauges start working?

If 12V is on purple wire and gauges work, turn key to start and measure 12V on yellow/redwire
If no 12V replace switch
If 12V is there, go to slave solenoid

Measure voltage on yellow/red small wire on slave solenoid when key is turn to start
If 12V is not seen, then a bad connection or wire from key to slave
If 12V is seen, use a larger jumper wire and jump across the 2 large terminals on top of slave solenoid. When terminals are crossed the start should engage

Thanks. I should have mentioned that I did measure voltage to the switch as well as to the starter, but not the slave solenoid.

My next question was going to be about jumping the starter, but you answered that as well. In the event that the solenoid nor fuse fix the issue, I still need to start the boat at least once so that is very helpful info.

 

[Chris1956]

Some of those Mercruisers have a resettable breaker on the block.