Resistor Wire

[LuckyPenny]

Does anyone know where the resister wire is located on a Mercruiser? is it in the harness from the control panal (dash) to the engine or is it located from the canon plug on the engine?

 

[rodbolt]

Re: Resistor Wire

its between the coil primary post and wherever your model spliced into the purple 12v key on + wire.<br /> some were at the cannon plug and some had a junction near the choke wire. why you wish to know ?

 

[fireship1]

Re: Resistor Wire

Do you suspect it to be defective? There are other ways around this if you don't feel like digging it out for replacement. Let us know what the trouble is, maybe we can help!

 

[LuckyPenny]

Re: Resistor Wire

I have a 1977 Mercruiser 250 HP (5.7L) and was having problems with burnt points. I checked the wiring and found that I was getting a straight 12V-13.5V at the primary. I should have been getting 7.2v-8.0 I installed a resister and everything is running fine, proper voltage and no more burnt points. Since I intend to do some rewiring I was looking at replaceing the resister with the proper resister wire, but can not find anything in any of the reference I have checked. So, if I can figure out which wire bundle it is in maybe I can get rid of the workaround and install the proper rig,

 

[rodbolt]

Re: Resistor Wire

your readings are a bit suspect, reading battery voltage at the coil positive primary with the points open is normal. the wire will increase resistance as current flows.<br /> but in the service manual for your particular harness will be the service specs and the parts manual will list the wire and if its avalible as a part or a harness.<br /> I dont think I have a manual at home that goes back that far.

 

[LuckyPenny]

Re: Resistor Wire

The readings are with the engine running. As for the location of the resistor wire, The diagrams I have just show a resistor wire in the circuit, not which bumdle it is located.

 

[fireship1]

Re: Resistor Wire

I replaced mine about a year ago on my Mercruiser 140. It was located right AFTER the cannon plug. It crimps in to the purple wire (12v hot when ignition is on) It wraps down the main engine harness doubles up and goes to the primary coil terminal. I too had the same problem. Points pitting up and coil overhating. Then when the coil got hot enough the engine would die. Restated fine when she cooled off. Ordered my wire from local Merc dealer. I was told I could have replaced the coil with the resistor built in to save all of the trouble. But wanted to keep the setup the way it came from the factory. Much like you do. If you need the Merc part number it's 84-94227A2 your wire sould read between 1.8-2.0 ohms when you test it. anything more or less and it's toast.

 

[fireship1]

Re: Resistor Wire

BTW, That part number is for the resistor wire by itself. You don't have to replace the whole harness. The cost was under $20.00 for this part.

 

[tootoot]

Re: Resistor Wire

My prob was opposite. Was getting 5 volts to the coil when I did the points check and took out resistor wire and replacd with sealed ballast. Spark now is like a cattle prod.