OMC Cobra 4.3L Electrical problems

[weslacey]

I'm about ready to give up on this boat and just bend over and take it to a marine mechanic. My 1986 VIP w/OMC Cobra 4.3L won't stay started. It fires right up but doesn't continue running. I've traced this back to the ignition coil, on the positive side. One wire gives power to start, the other gives power to stay running. So obviously the one that gives power to stay running is not getting any volts. I've traced this wire all the way from the alternator to the starter solenoid and still have the same problem. To fix this one problem i've replaced alternator, starter solenoid, and every dang fuse on that stupid engine that I could find. If I run a wire from the battery to the positive side of ignition coil boat runs fine. Please Help!

 

[WillyBWright]

Re: OMC Cobra 4.3L Electrical problems

Do you have a dead-man switch on that boat? Power to the coil goes thru that. Is the tether in place?

 

[cobra 3.0]

Re: OMC Cobra 4.3L Electrical problems

WAG: Could it be a wire(maybe a fusable link type) that looses contact(maybe a cracked wire) as the engine heats up? (Did you jiggle the wires when you were testing for continuity?)

 

[Boatin Bob]

Re: OMC Cobra 4.3L Electrical problems

That is your resistor wire, when you say you traced it all the way back did you actually test it with a meter? The book says if it goes you need to replace the wiring harness, if it was me I would just run another wire but then you would need to add an external resistor like a ballast type.

 

[I/O WALDO]

Re: OMC Cobra 4.3L Electrical problems

(Lanyard switch?)Is there ig.voltage at the back of the ig.switch,if so then it has to be either a connector or broken wire between ig.sw.and coil.

 

[DHPMARINE]

Re: OMC Cobra 4.3L Electrical problems

When cranking your engine,12 volts is supplied to your coil by the starter.When in the run position less volts (to preserve the points) is supplied by the alternator.That lead (between the alternator and coil) has a built in resistor wire.<br /><br />Bypass it (disconnect both ends) and add a new wire,using an external resistor and you'll be all set.<br /><br /><br />DHP

 

[weslacey]

Re: OMC Cobra 4.3L Electrical problems

So ya'll are saying disconnect the wire that runs from the alternator to the coil that gives it reduced voltage and add another with an external resistor? I tried running a new wire from the alternator to the coil but still got nothing... That was awhile ago so maybe i'll try again. Another question... i understand the purpose of a resistor but what is it? What does it look like and where can I get one? Is there a certain voltage that it needs to "resist" to the coil? I appreciate everyone's response! PS- there is no lanyard switch. <br /><br />This whole thing started at the end of last year when I decided to degrease the engine and wash it off. I thought i was careful to keep water away from the carb and other electrical components but guess not... thanks again

 

[bruceb58]

Re: OMC Cobra 4.3L Electrical problems

The resitor causes a voltage drop across itself. Should be around 9 Volts when the engine is running.<br /><br />You can also measure the voltage at the coil with the engine not running. Measure with the points closed and open. Open should read 12V and closed 9V-7V

 

[weslacey]

Re: OMC Cobra 4.3L Electrical problems

ran a wire from the alternator to the coil and still nothing. This stupid clymer manual was a flippin waste of money. Should have bought the OEM manual. Ran another wire from the positive side of the alternator and that works but the boat won't turn off when you turn the ignition off, you have to disconnect the wire. My stupid voltmeter is broken.... this is really frustrating. Any other thoughts?

 

[javsam]

Re: OMC Cobra 4.3L Electrical problems

does it have an oil pressure switch ?.seems to me I had a car once that would do the same thing,when started control voltage ran through the oil switch as a safety device.if oil wasnt present the switch shuts off motor.If it does try replacing oil pressure switch.<br />javsam

 

[I/O WALDO]

Re: OMC Cobra 4.3L Electrical problems

If the engine runs on a signal from the alt. how do you cut it off?There should be a purple wire that comes from the ig.switch/lanyard that feeds 12v to the alt.,the e.s.a.module,and the COIL.If it is open/dead ,no run!

 

[Boatin Bob]

Re: OMC Cobra 4.3L Electrical problems

Yes as Waldo says, check the purple wire for power with the key on, this also feeds power to your gauges so start there, have you pulled the big round main harness connector yet to check for corrosion inside? I know your frustrated but this shouldn't be that hard to fix.

 

[Sam freedom 195]

I'm in trouble, engine runs but gauges top out and don't work. Short somewhere, starter lazy though new starts but cable from battery gets hot any id as guys. Same engine

 

[GA_Boater]

I'm in trouble, engine runs but gauges top out and don't work. Short somewhere, starter lazy though new starts but cable from battery gets hot any id as guys. Same engine

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