Mercruiser 3.0 won’t fire

Blentz17

Seaman Apprentice
Joined
Feb 13, 2018
Messages
49
I have a mercruiser 3.0 alpha one I recently bought for a project. When I bought the boat the previous owner did not have the key so i replaced the ignition switch thinking I could test the motor and installed a new battery. The ignition was installed properly and the battery is fully charged, but when i turn the key the motor does nothing, no clicks or anything. The Gauges will move if I turn the key all the way to the Right which I am assuming is the run position but as soon as I let go of the key the gauges do go back to the off position. Because I hear no clicks I’m thinking the starter and the 50 circuit breaker which is popped may have something to do with it. Has anyone had any problems similar to this?
 
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Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,092
ign switch not wired correctly
control box in gear and neutral safety preventing starting
bad slave solenoid
 

Blentz17

Seaman Apprentice
Joined
Feb 13, 2018
Messages
49
The control box is the the neutral position.. The slave silonoid look pretty ruff so I’ll check that and the neutral safety switch
 

alldodge

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Staff member
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Mar 8, 2009
Messages
40,581
Check for 12V on the Yellow/Red wire at ignition switch when key is turned to Start.

If 12V is present, find the slave solenoid on top the motor. The solenoid will have a Yellow/Red wire on one of the large terminals and one of the small terminals. Turn key to Start and check for 12V on the small terminal of the solenoid.

If 12V is not present, its either a broken wire connection or the neutral safety switch in the shifter

If 12V is present, use a jumper wire or screw driver and cross the two larger terminals on top the solenoid. This is a Yellow/Red and a Red/Purple
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,684
The Gauges will move if I turn the key all the way to the Right which I am assuming is the run position but as soon as I let go of the key the gauges do go back to the off position.

All the way to the right is the start position.
When you let go of the key at that point it should go to the run position.
The gauges should operate in the run position.

If that's the case then the switch is wired incorrectly.
There may be other problems as well.
 

Blentz17

Seaman Apprentice
Joined
Feb 13, 2018
Messages
49
Let me clarify, the when I turn the key to the crank position .. all the way to the right the gauges work when the key is in the run position.. nothing .. The ignition switch is a three prong I've traced the wired twice and they are hookup up correctly.. so could this be the slave or the N Switch?
 

alldodge

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Staff member
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Mar 8, 2009
Messages
40,581
Let me clarify, the when I turn the key to the crank position .. all the way to the right the gauges work when the key is in the run position.. nothing

Marc C is correct its wired wrong. Red/Purple (common), Purple (run), Yellow/Red (start)
 
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