12 volts at ignition coil with Mercruiser 898 points distributor

[jas587]

The voltage at my ignition coil positve is 12V. For some reason there is a purple wire which is part of the ignition coil wiring at the end of my wiring harness not attached to anything. Now I am thinking that this purple wire is the resistance wire and needs to be hooked up somewhere in the engine harness. Should I attempt to troubleshoot this or install a pertronix where (my understanding) it needs 12V at the coil to work?

 

[muc]

Maybe somebody installed a internal resistor coil and re wired it?

 

[jas587]

Thanks Muc for the quick reply. I did purchase a new Sierra 18-5433 ignition coil from iboats that says uses external resistor, which I assume would be the resistor wire in the engine wire harness.

 

[muc]

I would troubleshoot, but I'm not a fan of pertronix. I understand some people love them. I would stick with points or go to an EST distributor.

 

[nola mike]

Some of the coils require a resistance wire, some don't. If yours uses a resistance wire, than the purple should be it.

 

[81 Checkmate]

Look in the sticky's - go to the manuals and look up your 898 year wiring diagram.... there are several different wiring diagrams for the 898. I think the purple wire is for your electric choke. May be wrong but you need to check it out.

 

[bruceb58]

Even with a resistance wire in the circuit, you will measure 12V if the point are open. With the points open, there is no current flowing hence no voltage drop.Close the points and then measure the voltage.

I would troubleshoot, but I'm not a fan of pertronix. I understand some people love them. I would stick with points or go to an EST distributor.

Totally agree. I would never use a Pertronix.

 

[jas587]

OK, thanks all for your input. Yesterday I completely went through the wiring harness checking it against the wiring schematic and it looked like every ignition circuit wire was where it needed to be. bruceb58, I never thought about the points being closed, right now the distributor is not installed, so I was checking it with the ignition on from coil postive to ground. The wiring harness does have a resistance wire loop with 2 ohms resistance, so my thought was that should drop the voltage to around the required 9 to 10 volts.

I have a new 350 sbc and SEI outdrive installed and need to run it at 2000 rpm for 20 minutes to break in the comp cams flat tappet marine cam, so don't want to burn up the coil at least until I get that done.

 

[bruceb58]

The wiring harness does have a resistance wire loop with 2 ohms resistance, so my thought was that should drop the voltage to around the required 9 to 10 volts.

Run a jumper between the negative post of the coil to ground. That will simulate the points closed.

With no current flowing, you won't get any drop.

 

[jas587]

Thanks bruceb58, will try that.