Starting Circuit Mystery (why won't my engine crank?) - Page 2 - SailNet Community
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post #11 of 50 Old 08-15-2019
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Re: Starting Circuit Mystery (why won't my engine crank?)

A solenoid allows a high amperage circuit to be energized by a low amperage circuit, nothing more. Take out the solenoid in an engine start circuit and you would need to run the battery cables to the starter button. Instead, you have a couple of #12 wires running from the switch to the solenoid, which has the battery cables attached for the starter. Push the start button and an electromagnet closes a circuit and the power can then flow through the battery cables.
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post #12 of 50 Old 08-15-2019
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Re: Starting Circuit Mystery (why won't my engine crank?)

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Originally Posted by BillMoran View Post
When I manually jump the wire at the button, the result is the same as if I pushed the button (i.e. nothing happens)
so I'd say you can eliminate the start button as the culprit.

and I'd say that your previous test seems to confirm that you can eliminate the starter/solenoid.

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Originally Posted by BillMoran View Post
Testing the amp draw on the solenoid and the starter is tough to do without help, so I haven't managed to do that yet.
understand.

for the solenoid circuit you can measure the amp draw at the push button ... it would be fairly easy solo and the values would be the same as "at the solenoid".

Do I understand correctly that when you push start nothing at all happens? no click, no slow crank?

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post #13 of 50 Old 08-15-2019
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Re: Starting Circuit Mystery (why won't my engine crank?)

Another thing in this line of discussion. Each of us should carry a remote start switch as pictured below to start the engine should the starting circuit fail. This can happen off the dock and if you have the remote start switch, it's less than a minute to hook it up and get the engine going!
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Re: Starting Circuit Mystery (why won't my engine crank?)

Forget ohms, if you hot wire the solenoid and it works then it is in the switch or switch wiring. Study up on using a voltage drop test. it allows you test every wire, connection or component with out removing any wires. it is simply reading the voltage drop at any point in the active circuit by placing the volt meter leads in parallel with the section that you want to test. tells you the voltage drop of the tested section.
https://www.freeasestudyguides.com/v...drop-test.html
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Re: Starting Circuit Mystery (why won't my engine crank?)

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Originally Posted by bristol299bob View Post
Do I understand correctly that when you push start nothing at all happens? no click, no slow crank?
To be very specific: nothing happens as far as I can tell ...

It's possible that the solenoid tries to close or something, but any noise that it makes is too quiet for me to hear from the cockpit.
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Re: Starting Circuit Mystery (why won't my engine crank?)

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Originally Posted by overbored View Post
Forget ohms, if you hot wire the solenoid and it works then it is in the switch or switch wiring. Study up on using a voltage drop test. it allows you test every wire, connection or component with out removing any wires. it is simply reading the voltage drop at any point in the active circuit by placing the volt meter leads in parallel with the section that you want to test. tells you the voltage drop of the tested section.
https://www.freeasestudyguides.com/v...drop-test.html
I understand how to do that ... the problem is that it's really difficult to do single-handed.
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Re: Starting Circuit Mystery (why won't my engine crank?)

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I understand how to do that ... the problem is that it's really difficult to do single-handed.
Very easy to do with long test leads and very hard to do the trouble shooting with out them. make a log test lead with a piece of wire

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post #18 of 50 Old 08-15-2019
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Re: Starting Circuit Mystery (why won't my engine crank?)

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Originally Posted by Skipper Jer View Post
Forget Ohm for a bit. What do you have at the solenoid when the start button is pushed? If it is less than about 12.6 start cleaning contacts.
Bingo!! I have seen many dirty contacts and bad switches that can pass a 0A voltage test easily but the minute they try to pass amperage, they fizzle out.

You can't test for this with the Ω setting of your DVM.... A volt-drop test on both the positive side and negative side of the circuit, under load, will give you the best information
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Re: Starting Circuit Mystery (why won't my engine crank?)

Relax ,trouble shooting this would be more difficult while dragging on a lee shore. If you don't have a fused button mounted in the engine area or the extendable wire unit Capta suggests . ???
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Re: Starting Circuit Mystery (why won't my engine crank?)

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Originally Posted by capta View Post
Another thing in this line of discussion. Each of us should carry a remote start switch as pictured below to start the engine should the starting circuit fail. This can happen off the dock and if you have the remote start switch, it's less than a minute to hook it up and get the engine going!
you are carrying a remote switch to be able to start the engine in a hurry why not just wire in the remote switch so you don't have to spend the time to connect it in a hurry. I was thinking of buying a second boat to tow behind so I would have a spare part for every thing on the boat with me.
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