mercruiser 3.7 has 6 volts at coil with key on

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rookie0423

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hi everyone I have a mercruiser 3.7 and Im not getting 12 v at the coil what should I check and how and if I need to replace anything , I can put a jumper on it and i will start but all the lights on the dash stay on , anyone have any thoughts or ideas ?
 
Don S

Don S

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Re: mercruiser 3.7 has 6 volts at coil with key on

What voltage do you have at the battery when you have 6 at the coil? There is a resistor wire in the system.
 
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stonyloam

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Re: mercruiser 3.7 has 6 volts at coil with key on

rookie0423 said:
hi everyone I have a mercruiser 3.7 and Im not getting 12 v at the coil what should I check and how and if I need to replace anything , I can put a jumper on it and i will start but all the lights on the dash stay on , anyone have any thoughts or ideas ?
Click to expand...

You should NOT have 12 volts at the coil with the key on. There is a resister wire (purple) between the coil and the choke that drops the voltage to about 6-7 volts. Measure the voltage at the choke end, should be battery voltage. The resister wire should give a 1.8 to 2 ohm resistance. The only time the coil sees battery voltage is during starting, when it gets its voltage from the slave solenoid (purple/yellow wire).
 
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rookie0423

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Re: mercruiser 3.7 has 6 volts at coil with key on

my battery has 12.3v and the coil has 6.45 with key on , wen trying to start it it should jump to 12v correct , but mine drops to 5v when trying to start it , what should i check
 
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rookie0423

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Re: mercruiser 3.7 has 6 volts at coil with key on

could this be my slave solenoid and how do i check it if it is
 
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searay3

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Re: mercruiser 3.7 has 6 volts at coil with key on

Have the battery load tested
 
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searay3

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Re: mercruiser 3.7 has 6 volts at coil with key on

Are you dropping to 5 volts when cranking the starter on a new battery? Check the battery cables at both ends. If that checks out, have the starter checked.....it is drawing to much.....
 
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stonyloam

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Re: mercruiser 3.7 has 6 volts at coil with key on

rookie0423 said:
my battery has 12.3v and the coil has 6.45 with key on , wen trying to start it it should jump to 12v correct , but mine drops to 5v when trying to start it , what should i check
Click to expand...

It sounds like you may have a bad contact in the slave, or a poor connection either at the coil or slave terminal. disconnect the p/y wire from the coil and measure the voltage while the starter is turning, also measure the battery voltage while the starter is turning. They should be the same.
 
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