purple resistance wire heating up at coil

zannidave

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Jul 28, 2013
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hi im new to the site and I see there is a lot of great information here. so if I could pick some brains hopefully I can get an answer to my dilemma. I just bought a 89 regal with and I/O mercruiser 3.0 engine, the ignition has a pertronix ignitor, brand new stock sierra coil, new distributor cap, rotor, and wires.
ok so the issue is when I turn key to the on position the purple resistance wire from the boat harness heats up real quick and stays hot to the touch. when I test the voltage at the + side of coil there is no voltage but when I take the wire off of the + side and let it hang free I have 12 volts and the wire cools down im not sure what is going on here. its a new coil and it does the same thing with the old coil I replaced too. when I crank the motor the starter provides 8 volts to the coil but no spark. im a little lost as to whats going on here. im almost positive that the wire is not supposed to get hot and im supposed to have anywhere from 8v to 12v while the key is run. if there is something I have missed(which is more than likely) would someone please be able to point me in the right direction. thank you
 

hivoltg

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Jul 15, 2013
Messages
186
Re: purple resistance wire heating up at coil

Welcome to the site zannidave. Can you post an engine serial number we can all see the wiring diagram for what you are working on.

Usually on merc purple = power wires.
 
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zannidave

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Jul 28, 2013
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Re: purple resistance wire heating up at coil

ok ill have that up first thing in the morning. along with a picture of what ignition set up im dealing with, maybe it will help better to see whats going on. thank you for the quick reply
 

tank1949

Lieutenant Commander
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Apr 4, 2013
Messages
1,759
Re: purple resistance wire heating up at coil

Might want to buy extra coil for THAT motor. If you bought boat used, no telling who or what has swapped parts. Some coils use external resistors or resistors are built into wire, and other are internal to coil. I suspect external. The purple wire, if my old memory works, is the hot lead coming from Altenator. Get yourself a GOOD manual and "dig."
 

hivoltg

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Jul 15, 2013
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Re: purple resistance wire heating up at coil

I was thinking the same thing tank1949 that purple from the alternator is notorious for shorting when the plastic cap falls apart but it could be the purple from the key also. I wanted to see his diagram & pics first.
 

alldodge

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Mar 8, 2009
Messages
40,582
Re: purple resistance wire heating up at coil

Welcome to iboats

The purple resistance wire comes from the choke. Since you get 12V when removed you have a short from either your coil, the purple/yellow wire going to the starter or something is miswired. Look on page 4 for your proable wiring diagram. As mentioned previously your serial number will help a lot.

http://www.google.com/url?sa=t&rct=...4qQi8VZFY1JEgo10g&sig2=cK6kK1-hwDiOsUWSU_F2Nw
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: purple resistance wire heating up at coil

Those numbers are for a 1988 MERCRUISER W/O PS 3.0L ALPHA...

Chris.....
 

zannidave

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Joined
Jul 28, 2013
Messages
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Re: purple resistance wire heating up at coil

OK so I even put a clean 12v to the + on the coil and crank the motor and I only get one spark it orange blue spark but it doesn't spark again while cranking. I'm not sure what this means....maybe bad pertronix ignitor? Not sure. I disconnected the electric choke the purple wire gets hot, i disconnected the starter purple/yellow wire from the terminal and the wire with the wire still attached to the new coil I bought yesterday and the purple wire still gets hot. If I leave the coil disconnected and the starter purple/yellow wire connected to the starter the purple wire still gets hot. If it is supposed to get hot if the motor is not running I guess i can understand that. But then why am I getting only one spark at the end or beginning of cranking....I am stumped.
Another thing is whenever I put any voltage to the purple resistance wire it gets hot, even with the key off. But I checked the resistance and continuity to ground and I get nothing...so I'm sure there is no short to ground...
I appreciate everyone who is helping me.
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: purple resistance wire heating up at coil

If you left the key on while the engine was not running you could have burnt the unit. The ignitor II has protections for that.
 

hivoltg

Petty Officer 2nd Class
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Jul 15, 2013
Messages
186
Re: purple resistance wire heating up at coil

zannidave, test that coil:

coil_checks.jpg

Specs range in the pic above for both internal and external ballast coils.
 

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Perkins2652

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Jul 8, 2013
Messages
8
Re: purple resistance wire heating up at coil

I have the same problem on my merc 260 hp replaced alot and it still heats up
 

zannidave

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Jul 28, 2013
Messages
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Re: purple resistance wire heating up at coil

hey hivoltg im sorry I didnt try to test it. im a little over zealous with my troubleshooting and im probably overlooking some of the simple things. tomorrow I will start there. I appreciate the measurements over the coil I will compare.
I went over the wiring and had to remake some of the connections for wires i.e. the alternator and starter wires thank you tank1949. i also found in the harness from the motor to boat the contacts were oxidized and really loose. I spread the blades a bit and put dielectric grease in it. and it did fix other issues I was having lol
I did find that the starter post with the yellow/red and the purple/yellow with nothing attached to it gets 2v when the ignition is on. im not sure if its supposed to do that or is contact bad??
im under the impression that it is supposed to be clean with nothing on it when the ignition is on, but im honestly not sure
 

zannidave

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Joined
Jul 28, 2013
Messages
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Re: purple resistance wire heating up at coil

Ok so I just tested the new coil I bought and the primary side is 1.6 ohms and the secondary is 9.02k ohms. The old coil I have the primary reads 1.8 ohms and the secondary is 10.37k ohms that's where I stand with the coils hivoltg.
 

hivoltg

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Jul 15, 2013
Messages
186
Re: purple resistance wire heating up at coil

Ok so I just tested the new coil I bought and the primary side is 1.6 ohms and the secondary is 9.02k ohms. The old coil I have the primary reads 1.8 ohms and the secondary is 10.37k ohms that's where I stand with the coils hivoltg.

1.7 on an external resisted coil is spec. I accidentally posted the internal resistant coil specs test pic. :facepalm: Both your coils sound good.
 
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zannidave

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Jul 28, 2013
Messages
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Re: purple resistance wire heating up at coil

Ok great I as worried for a moment. Is there anything else you can think of that I may be missing? I was thinking due to the nature of the resistor wire getting hot should i change over to a 3.0 ohm coil to remove the resistor wire and elimate the problem all together?
 

hivoltg

Petty Officer 2nd Class
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Jul 15, 2013
Messages
186
Re: purple resistance wire heating up at coil

I changed on my boat to an internally resisted oil filled coil. (They actually have a lower ohm reading *on the primary side*, not higher)

The thing im not sure on is your electronic choke. It sounds like your boat uses the purple to adjust its choke. Someone will need to confirm this.
 
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zannidave

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Joined
Jul 28, 2013
Messages
14
Re: purple resistance wire heating up at coil

Ok so I traced the resistor wire to a crimp connector right after the motor harness connector. It crimps to the purple wires the go to two locations, the first is the choke and the second is the alternator. So you are correct that it does adjust the choke. I confirmed that the choke is not shorting out and neither is the alternator. I'm going to continue troubleshooting after I run some errands today on the pertronix side.
 
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