now, to get power to my coil

[biggjimm]

I've got two questions regarding getting power to my coil as there are two power sources & they're both dead. It's my '76 140 mercruiser.

1) I've lost power from the key switch thru the resistor wire. I've got power on the wire (white wire) from the key switch to the gauges & coming off the last gauge & into the harness but nothing at the other end. I'm not going to cut open the whole harness & was just going to run a new wire from the helm back to the engine. Can I get a new resistor wire, or do you have to replace it with a ballast type resistor?

2) my solenoid is not sending power to the coil during cranking neither. I was looking at a buddies boat this morning which is the same 140 set up as mine & his 12v to the coil during cranking is coming from the slave solenoid & not the starter solenoid. It's on with the big yellow wire that goes to the starter solenoid which is 12v during cranking also. He said he's had this boat for over 20 years & it must have been that way when he got it as it's never been to the shop & he didn't do it. Is this an ok alternative to getting the cranking voltage from the starter solenoid? Apparently it works or at least has for him. What, if any, long term problems could that setup cause. Supposedly he hadn't had any problems with his boat starting or running & they run that thing almost every weekend. Thanks. Jim.

 

[bruceb58]

As far as the resistor wire, easiest thing to do would be to just wire in a ballast resistor an mount it to the block.

 

[stonyloam]

You can get a new resistance wire, but it is crazy expensive, 25 here: https://www.mercruiserparts.com/Show...CAL+COMPONENTS. Agree with Bruce, an external ballast should work fine, as I recal it is 1.8 Ohm, will double check that. Yeah wire the coil to the large switched terminal of the slave. Should work just fine, there is only voltage on that terminal when the starter is engaged.

 

[Eric 3.7LX Alpha 1]

The solenoid needs to have 2-small posts.. one marked "S" gets power from the ignition during cranking only.

and one marked "R" which will give 12-volts power to the coil during cranking.

With the key in the "run" position, the "R" post on the solenoid will be showing voltage on it, received from the coil thru the resistance wire, it will be dead-ended, but on the wrong solenoid terminal might energize the starter solenoid.

Just make sure you don't wire the coil to the same small post on the solenoid that the ignition switch is, or your new wire will be powering the solenoid as soon as you let off the key and the starter won't stop cranking.

The resistance wire is Mercury-Wire Kit #84-94227A2

 

[bruceb58]

I am revising my comment about wiring to the slave. That might allow the starter to energize. That is unless the slave has 2 terminals on it.

 

[biggjimm]

The slave has two terminals on it. I've already had it jumpered & it seems to works perfect. But now I wonder about when I get the resistor wire fixed, if that will send voltage to the slave & try to engage the starter? I think that presents a problem. Perhaps a, what is that gadget that only lets current flow one way thru a circuit? An electrical check valve of sorts. That might stop the resistor wire from energizing the slave?

Could a guy wire up a relay to get coil voltage directly from the battery during cranking. I'm not trying to be a cheap skate just trying to keep from standing on my head & taking this starter off, lol.

 

[stonyloam]

Oops, yeah the feedback from the coil would engage the starter solenoid. Relay, sure could like this one: http://www.summitracing.com/parts/mrf-mp-1025 power the relay off of the slave, so that it engages when you hit start. Run power directly from the (hot) side of the slave to the normally open switch, then directly to the coil. I use one almost exactly like this to power my Petronix ignition, works fine.

 

[stonyloam]

Just for the heck of it, does your slave look like this? https://www.mercruiserparts.com/show...asp?pn=25661T1 Does it have a black wire on one of the small terminals? If it does you need the relay to make it work. I was thinking it was a switched relay like on my 470, that works differently. Even though it looks exactly the same.

 

[biggjimm]

This is my slave solenoid.

http://www.iboats.com/Solenoid-18-58...view_id.172064
It does have a black wire on the other little post, opposite of the little yellow coming from the key switch, it goes to ground. I think the easiest thing is to put a relay in for my "crank" signal & a new wire from the key switch with a ballast resistor for my "run" signal to the coil. Thanks.

 

[biggjimm]

For some reason it blurred out the link. Try this one.
http://www.iboats.com/Solenoid-18-58...view_id.172064

Not sure why it's blocking blocking the other website but anyway my slave is Sierra part # 18-5815

 

[Fun Times]

Not sure why it's blocking the other website but anyway my slave is Sierra part # 18-5815

Some websites are considered financially competitive to iboats so they have been preprogrammed to automatically be blocked out. The Administration here doesn't prefer to advertise for them on their site...Just financial business strategies at work is all. That website you mentioned is one of them. Sorry for the inconvenience. I've repaired the links with something similar though. Good luck.

 

[Bondo]

Ayuh,.... I'm wonderin' Why ya can't use the tiny outside terminal on the starter's solenoid, like it's supposed to be,..??..??

 

[biggjimm]

Ayuh,.... I'm wonderin' Why ya can't use the tiny outside terminal on the starter's solenoid, like it's supposed to be,..??..??

To be perfectly honest bondo, I don't feel like standing on my head to pull the starter off. Every other aspect of the starter/solenoid works fine & I've got all the necessary components to wire up a relay. If it'll work & be safe, then why not?

 

[stonyloam]

Ayuh,.... I'm wonderin' Why ya can't use the tiny outside terminal on the starter's solenoid, like it's supposed to be,..??..??

He is not getting voltage on that terminal, might be a bad contact or broken wire.

 

[biggjimm]

Long story short, I found break in white wire behind shifter. Fixed it & I've got voltage from the resistor wire to coil + for "run" signal. Found cruddy ground at engine block, fixed that & I've got 12v from the solenoid to the coil + for "crank" signal. So I removed the relay that I had just wired up & it's all working perfectly. Thanks everyone.

 

[Eric 3.7LX Alpha 1]

Nice! Glad to hear the news! :thumb:

 

[stonyloam]

Great!

 

[biggjimm]

Well, it's almost perfect. The "run" voltage coming from the switch is full battery voltage, almost 13v at idle. Apparently there is not a resistor in the harness??? The engine harness has been cut apart & all taped up at some point in its life. Also I just talked to the previous owner & he said that he had a lot of problems with coils going bad when he had it & we've had trouble before with the coil too. I'm guessing not having a resistor burns the coils up after a while? Going to order the resistor wire in the morning.

 

[bruceb58]

Or just get a ballast resistor. Might be a lot cheaper.

 

[biggjimm]

$17.99 for ballast & $19.99 for the wire.