Implications of burnt out resistor wire

[tschmidty]

I have a 1988 3.0. Running OK, but I noted I am getting 11.5V at the coil (stock) when idling. Per other posts I should be seeing 4-9V or so, so I am guessing my resistor wire is bad. From what I understand, what will happen in this case is I will be burning out my coil and points quicker. Is that correct? Also, are there any performance implications to having the voltage that high? Runs well, but I am only getting 4000 RPM at WOT with a 19" 4 blade propeller. I have maybe seen 4100-4200 with a 19" 3 blade prop.

 

[Aloysius]

Re: Implications of burnt out resistor wire

If the resistor wire defective you'd get ZERO volts at the coil.

 

[thumpar]

Re: Implications of burnt out resistor wire

Your resistor wire might have been changed out for a regular wire if the coil was changed out before you got it. I changed mine out a few years ago. If it is stock coil I would get it fixed.

 

[LAC_STS]

Re: Implications of burnt out resistor wire

If the resistor wire defective you'd get ZERO volts at the coil.

NOT true. I just replaced my resistor wire with a ballast resistor.

I have been fighting an intermittent bogging and setimes backfiring not going over 3K RPM issue.

I replaced everything from the fuel line to rebuilding the carb to a bunch of stuff.

Then last week I had an electritian out fishing with Me and the boat started backfiring. He hooked a jumper wire from batt to coil and the boat took off like it never had before.

I replaced the old resistor wire with a ballast resistor and all is well now. The boat runs better than ever and the coil doesn't get as hot as it used to.

I think that after a long time the resistor wires dot hold the same resistance and they don't cool down like they're supposed to when the throttle is opened up.

Ballast resistors are cheap. Like $15. Get a new one and rule that out.

 

[LAC_STS]

Re: Implications of burnt out resistor wire

Oh yea,

Or wire could have been cut before too. It says in the manual to never cut the resistor wire because it will change it's resistance.

 

[Aloysius]

Re: Implications of burnt out resistor wire

Obviously the resistor wire was deteriorating, and the voltage to the coil was dropping, because the resistance was increasing. The jumper put a full 12 volts or more to the coil.

A resistor wire is like a carbon string core plug wire..broken plug wire delivers 0 volts.

Ballast resistors are the way to go if you don't want to use an internally ballasted coil.

 

[ChrisCraftJohnny]

Re: Implications of burnt out resistor wire

Does the resistor wire run all the way from the ignition switch to the coil?

 

[thumpar]

Re: Implications of burnt out resistor wire

No. It runs down to the starter if I remember correctly. I do know that is runs down to the backside of the motor. It is not real long.

 

[LAC_STS]

Re: Implications of burnt out resistor wire

Obviously the resistor wire was deteriorating, and the voltage to the coil was dropping, because the resistance was increasing. The jumper put a full 12 volts or more to the coil.

A resistor wire is like a carbon string core plug wire..broken plug wire delivers 0 volts.

Ballast resistors are the way to go if you don't want to use an internally ballasted coil.

My resistor wire was not broke nor did it look in bad condition. it wa old yes but it looked alot better than a lot f other wires I have found on the boat. And especially for a wire that gets so hot all the time.

Prob lem was that when I would be at idle speed for more than a quick min then try to go it would not cool down. Even if I kept trying and kept the engine over 3K RPM for 30 mins the thing would still be limp and too hot too touch. added ballast resistor and voila problem gone. the wire is still there taped up. It goes into a 3 wire splice before going to the alt so I didnt want to cut it out.

No. It runs down to the starter if I remember correctly. I do know that is runs down to the backside of the motor. It is not real long.

On my 5,7 OMC the resistor wire is the one that goes to the alt. The wire that goes to the starter is the one that gives the coil a full 12V when you start it. (ie while cranking)

Get a meter and check continuity if your not sure, or if your wires go into a harness of some type. Disconnect the 2 wires at the coil.

Then put one probe on one wire and then the other probe on the correct terminal on your alt. If it beeps thats your wire. If it doesnt beep try the other.

 

[thumpar]

Re: Implications of burnt out resistor wire

On my 5,7 OMC the resistor wire is the one that goes to the alt. The wire that goes to the starter is the one that gives the coil a full 12V when you start it. (ie while cranking)

That is right. I knew it was one of the 2.