OMC Ignition. Starts then fails

[pkaufman]

I have been reading some related posts to this problem that are similiar to mine. 1987 OMC 5.7 engine starts fine. Turn off key then stops. If I keep key on then motor gets spark.Turn key off runs then dies. I assume it is the resister somewhere in the wiring that cuts the voltage from 12 to 9. A direct lead from the + battery to the coil will keep the motor running. However all this voltage gets the coil red hot. <br />I cannot find where the resister is!!! to bypass it.I have ordered a OMC manual and hope that pinpoints the location.<br />Does anyone know the location or if I am on the right track here? Two mechanics have told me to bypass the resister and the bypass from the battery to the coil does indicate the resister is bad...but cannot find it to bypass or replace.<br />Thanks in advance.

 

[Boomyal]

Re: OMC Ignition. Starts then fails

I am not positive on your year OMC, but earlier versions used a 'pot' resistor as opposed to an inline 'wire' ballast resistor. If it is the pot type, it should be mounted at the back of the motor. It'll have two wires clipped on to it. It would have a metal frame with a white composite material in it. <br /><br />If it is an inline 'wire' type. Someone, here should know where it is located.

 

[elpaso]

Re: OMC Ignition. Starts then fails

I have wiring semantic, but can not figure out how to post it.<br /> <br />Quick fix - This will work with points and condenser,or electronic ignition. <br />Remove the 2 wires from + side of coil. The purple and black <br />wire should have 12 volts, "only" when starter is turning. <br />This gives you a hot 12 start. The 2nd wire, purple and red is<br />ignition, 12 volt when key is on. If resistor is blown - no voltage.<br /><br />If you have no ignition voltage, block that wire off.<br />Find main engine cable connector, the purple wire feeds the <br />alternator and coil. Splice into this wire, remember alternator<br />still needs power. Install a "bar" type resistor into new wire,<br />and run to + side of coil. This will give you 8-9 volts to run on,<br />and wire from starter solenoid will give a 12 volt hot start.<br />Old resistor has been bypassed.<br /><br />The bar resistor was used on many Chrysler cars 72-84. <br />There are two types open back, you will see a spring - and<br />solid back - sealed spring- you want solid. About $5. Any<br />auto parts. <br /> <br />Check each wire with a test light, with an old boat, who knows how many thing have been changed.<br />If coil has been hot, it may be damaged - also replace points and condenser.

 

[pkaufman]

Re: OMC Ignition. Starts then fails

Thanks a lot. I'll try this out. If you want can send semantic to pkaufm@adelphia.net

 

[Boatin Bob]

Re: OMC Ignition. Starts then fails

Your resistor wire should be the purple w/red tracer goin to the pos side of the coil, it hen goes through a connector and becomes the purple wire at the alternator. Resistance should be 2 +-.5 ohms. OMC shop manual says if it goes you have to replace the wiring harness. If it's truly gone then you can probably bypass it with one of the ballast resistors as Elpaso said.