No crank

[nickmo]

Mercruiser 5.0 TKS. I started motor, was idling a minute or 2 then just stalled. I tried to restart, had no buzzer, no lights, no horn and no click or crank. Battery is new and reading 12.8 volts. Battery cables are clean and tight. Circuit breaker behind carb is not tripped. Any help appreciated.

 

[alldodge]

Check the 20 amp ignition fuse. Its either an inline fuse behind the helm attached to the red/purple wire, or breaker

 

[nickmo]

Thanks for the response. There is a fuse box under the helm that has a 15 amp ignition fuse. I checked it and it is not blown. I applied 12 volts to the wire that supplies the fuse box and everything works including the engine starting and running. When I remove the power, the engine stalls.

 

[alldodge]

Check the 50 amp breaker on the motor.
If no power there check the 90amp fuse on the main starter post

 

[nickmo]

There is power on both sides of the 50 amp breaker. There is 12.8 volts at the orange wire to the alt. Would that confirm that the 90 amp fuse on the starter is good? Someone suggested checking the slave solenoid, but I can't find anything that looks like it on top of the motor.

 

[Scott Danforth]

go to the back of the ignition switch. do you have power on the red wire, yes or no. if yes, check the purple wire. do you have voltage on the purple wire when the key is turned, yes or no

the orange wire on the alternator goes directly to the battery at the starter, it will always have battery voltage

 

[alldodge]

There is power on both sides of the 50 amp breaker. There is 12.8 volts at the orange wire to the alt. Would that confirm that the 90 amp fuse on the starter is good? Someone suggested checking the slave solenoid, but I can't find anything that looks like it on top of the motor.

Someone must have done some rewiring
With power on the 50amp, then there should be power on the key switch red/purple

Before you turned the key are there was nothing, not even gauges.

 

[nickmo]

go to the back of the ignition switch. do you have power on the red wire, yes or no. if yes, check the purple wire. do you have voltage on the purple wire when the key is turned, yes or no

the orange wire on the alternator goes directly to the battery at the starter, it will always have battery voltage

No power at the red wire and no power at the purple when key is turned.

 

[nickmo]

Someone must have done some rewiring
With power on the 50amp, then there should be power on the key switch red/purple

Before you turned the key are there was nothing, not even gauges.

I've owned the boat since new. Don't think any wires were changed. No gauges had no power. I ran a wire from the positive side of the battery to the red/purple wire that powers the fuse box. Everything got power including ignition switch which then started the motor.

 

[alldodge]

I've owned the boat since new. Don't think any wires were changed. No gauges had no power. I ran a wire from the positive side of the battery to the red/purple wire that powers the fuse box. Everything got power including ignition switch which then started the motor.

OK, then pull the 10 pin connector apart, I'm thinking the red/purple which is pin 6 has corrosion or is broken

 

[nickmo]

OK, then pull the 10 pin connector apart, I'm thinking the red/purple which is pin 6 has corrosion or is broken

Thanks. That will be my next move. I'll report back tomorrow.

 

[nickmo]

The pin in the connector was burnt. I don't understand having a 50 amp breaker protecting a 16 gauge wire. Anyway spliced in a wire bypassing the connector and everything is good. Many thanks to all and especially Bt Docktur.

 

[alldodge]

The wire should be 12 gauge, but in any case, the 50 amp supplies power to the rest of the motor as well. The slave reay to the starter is another heavy load

 

[Bt Doctur]

The slave relay to the starter is another heavy load Except all that wiring and the cube relay are the same small gauge