Re: mercruiser eating coils

ledrenken · Jul 4, 2013

Re: mercruiser eating coils

pentland said:
thanks for the reply i think i'll try one of those coils.

I too have a 1995 4.3 mercruiser 180hp with thunder bolt ignition and I did try a MSD coil and sorry to say that it worked for about 10 mins, I really don't know why this boat keeps burning up coils, I have replaced at leased 5 coils over 6 years, I have been told that this could be the ignition module, I really don`t want to start replacing expensive parts if I am just guessing, is there a way to test this? I know that I can put in this new mercruiser coil and the boat will run good for some time, just how long, ?? HELP

Bondo · Jul 4, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

ledrenken said:
I too have a 1995 4.3 mercruiser 180hp with thunder bolt ignition and I did try a MSD coil and sorry to say that it worked for about 10 mins, I really don't know why this boat keeps burning up coils, I have replaced at leased 5 coils over 6 years, I have been told that this could be the ignition module, I really don`t want to start replacing expensive parts if I am just guessing, is there a way to test this? I know that I can put in this new mercruiser coil and the boat will run good for some time, just how long, ?? HELP

Ayuh,.... Welcome Aboard,... I pulled yer post outa that thread from 2003, 'n gave ya yer own thread,...

Please respect our posting rules listed at the top of the main forum,...
And,... The Big Red Banner that asked you to start a thread, rather than postin' to an antique thread,...

That said,....

What is the voltage, at the coil's (+) terminal,..??

oldjeep · Jul 4, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Makes me wonder if there is supposed to be a ballast resistor in front of the coil. What you are describing is usually what happens when a standard coil is getting 12V all the time rather than just for a bit at startup. Happen to have a wiring diagram for your boat?

gm280 · Jul 4, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

oldjeep said:
Makes me wonder if there is supposed to be a ballast resistor in front of the coil. What you are describing is usually what happens when a standard coil is getting 12V all the time rather than just for a bit at startup. Happen to have a wiring diagram for your boat?

I too thinks it sounds like a current limiting (ballast) resistor is needed. If you knew the resistance of your coil. you could figure out what valve and wattage you need to install...

Bt Doctur · Jul 4, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

does this include OEM coils? whats the voltage at the + side of the coil with the motor running at 2000rpm?
Only points use ballast resistors TB`s run battery voltage.

ledrenken · Jul 4, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Bond-o said:
Ayuh,.... Welcome Aboard,... I pulled yer post outa that thread from 2003, 'n gave ya yer own thread,...

Please respect our posting rules listed at the top of the main forum,...
And,... The Big Red Banner that asked you to start a thread, rather than postin' to an antique thread,...

That said,....

What is the voltage, at the coil's (+) terminal,..??

I have the Thunderbolt ignition, With a new Sierra coil running at 1,000 rpms I have 14.5 at the battery and 10.o on the + side of the new coil, Is this low ?

ledrenken · Jul 5, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Is 10 volts ok at the coil, this is with the thunderbolt ignition

ledrenken · Jul 6, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Thank`s for all the help, guess I will try find the problem my self,

Bondo · Jul 6, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

ledrenken said:
Thank`s for all the help, guess I will try find the problem my self,

Ayuh,... There are diagnostic trees up in the Adults Only section, at the top of the forum,....

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Bond-o said:
Ayuh,... There are diagnostic trees up in the Adults Only section, at the top of the forum,....

Hi again,I Still can`t figure out this boat, With the key on I have 12.8 in & 11.8 out at the ignition switch, Running I have 13.3 in & 13.3 out at the ignition switch but only 10.9 at the coil, And with the key on not running I have 11.7 at the coil, any ideals?

Don S · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Running I have 13.3 in & 13.3 out at the ignition switch but only 10.9 at the coil,

Disconnect the purple wire on the choke, and see if the voltage goes up. Do the same thing to the purple wire on the alternator (Excite wire) and see if the voltage comes up.

Might even check the voltage going to those units as well. Should be more that 10.9.

You should also be seeing ~14.5 running not 13.3

With the key on I have 12.8 in & 11.8 out at the ignition switch

Do a voltage dropdown test on the ignition switch. Put the red meter test lead on the B (Battery) terminal of the switch, and the black meter test lead on the I (igntion) terminal of the switch and see what reading you get.

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Thank you for the help, I will check that out and get back soon, Thanks

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

With the purple wire at the alternator disconnected the volts stay the same, have 11.6 at this wire & still 11.6 at coil, the purple wire for the choke is not hooked up don`t see any place for that? have 11.6 on this wire, on that switch I get 12.7

Don S · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

What's the serial number of your engine? and what carb do you have?

Merc doesn't even list a 180hp in the manual.

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Serial # 0F370607 4.3 LX/ V6 Thunderbolt IV Ignition with a Weber WFB

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

This is in a Star Craft 2012 - 1995- I am at a loss,

Don S · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

You need to find out where the voltage is going. That will probably cure the coil eating problem as well.

Could be a loose or corroded connection somewhere, or a defective wire or component.

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Ok I will check for that, Thanks for helping , Let you know what fined

ledrenken · Jul 13, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

Well I guess I am in over my head, Going to get some help, will let you know just they fined, Thank you

FuelishBehavior · Jul 14, 2013

Re: mercruiser eating coils

Re: mercruiser eating coils

I found that I had a bad short on one of my batteries positive cables behind the engine. It ate coils and now has ultimately ate the ignition module. Good luck

Re: mercruiser eating coils

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