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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11073
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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2000 ocean pro 150. Starter spins doesn't engage. Have 12 v

Customer Question

2000 johnson ocean pro 150. Starter spins doesn't engage. Have 12 v at key on red/purple. Turn key 13 volts on yellow /red at key. Both batteries charged 100%
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

We need to test the voltage at the battery cable connection on the start solenoid when cranking and at the starter terminal. Test both locations while cranking the engine.

What is your voltage reading?

Customer: replied 1 year ago.
Looking at solenoid terminal on right has red wire going. It has 12 v. Has son turn key and terminal to left has around 4 volts. That terminal has a short wire strapabout an inch long that goes from solenoid terminal to starter terminal on front side.
Expert:  Tan replied 1 year ago.

Ok you are loosing voltage to the start solenoid. The minimum voltage required for the starter to work correctly is 9.5 volts. Check all the battery cable and connections. If you have a battery switch bypass the switch and check starter voltage again.

There is a test we can do to determine which cable is bad. Connect the black meter test lead to the negative post of the battery and the red meter lead to the start solenoid battery cable connection. Now crank the engine over what is your voltage reading?

If the voltage is less than 9.5 volts then you have a bad positive cable or connection. Now connect the red meter test lead to the red battery post and the black test lead to the engine ground. Now crank engine. If voltage is less than 9.5 volts you have a bad battery cable or connection.

If you have a set of jumper cables jump the starter directly on the cable that runs from the solenoid to the starter.

Post back with voltage readings.

Customer: replied 1 year ago.
Both batteties are new and 100% charged. I have 12.5 on one side of solenoid but 4 on other side of solenoid.
Expert:  Tan replied 1 year ago.

Ok you should have 9.5 + volts on both sides of the solenoid. If you have 9.5 volts on the battery cable side and less than 9.5 on the starter side of the solenoid the solenoid is bad. Both of these checks have to be done when cranking the engine.

If you have a bad battery cable or connection when you load the circuit the battery voltage will drop below 9.5 volts.

All the tests I have outlined have nothing to do with the condition of the batteries. These are load tests for voltage delivery to the start solenoid.

Post back with findings and questions.

If the cable, connections or solenoid don't deliver the correct voltage to the starter it will not function correctly.