OMC Cobra Ignition - No spark from ignition coil

[Liv2fish2]

Hello, I am having problems getting my OMC engine to start. I have a 1987 OMC Cobra - GM 350 V8 with a Mallory single point distributor. This engine is mated to the corresponding Cobra outdrive - complete with E.S.A. circuitry. The main problem started showing itself on my last outing, when it would run well for a while and then die for no reason. After another full day of running without problem, I figured it was a fuel clog or something. The boat was put away for the season after this trip and now will not start at all. It will not even show a spark coming off the high tension wire from the ign. coil. I have rebuilt the distributor with points, rotor, condenser, cap, etc. I replaced the ign. coil with the same model coil, as well as the ignition key switch. I have pulled off all ignition wire connections (that I could find)and cleaned any corrosion (which was very little). The boat only sat a couple of months w/ stabilizer in fuel. I have taken the voltage reading tests as outlined in the owner's manual, and everything so far checks out (voltage to coil '+' side, voltage to points - with motor cranking & with ignition just in "on" position. The starter motor cranks, gauges work, trim/tilt works, basically everything except for my secondardy ignition voltage. My last thoughts are that I have a bad ground at the distributor casing to the engine block. I am thinking about running a new ground wire from the block to one of the side bolts on the distributor. Any responses or suggestions would be greatly appreciated. I would love to be able to handle this problem myself and not have to tow it to a shop - just yet. Thanks!

 

[BigBabyLou]

Re: OMC Cobra Ignition - No spark from ignition coil

If you suspect bad distributor ground, you can easily check by momentarily grounding the negative terminal of the coil. Provided the coil has good voltage at the positive terminal, it should give you a good spark. If it doesn't, it's either lack of voltage on the positive terminal or the coil itself.<br /><br />The coil is powered from ignition through a resistor wire. There is also a bypass (for the resistor wire) from the starting solenoid (to produce better spark during starting). If the resistor wire is old, deteriorated and falling apart, it might show good voltage when coil not in use but the actual voltage when inducing spark will drop below working range and you won't get any spark. For testing purposes, you can always (ONLY TEMPORARILY) connect +12V to the coil positive terminal and try grounding the negative terminal. If you don't get a spark then, the coil must be the problem.<br /><br />Hope this helps.<br />Lou

 

[Liv2fish2]

Re: OMC Cobra Ignition - No spark from ignition coil

Thanks for the thought Lou. I forgot to mention that when cranking the engine, I get a reading of 8 volts on + coil side. I think I may replace the resistor wire as it has some age (1987). Is this wire available at Marine supply shops only, or can this be from an auto store? Thanks.

 

[BigBabyLou]

Re: OMC Cobra Ignition - No spark from ignition coil

8 Volts ... How much do you have on the battery when starting? If the voltage difference is under 1V, I would say it's fine. Otherwise I would be looking at the bypass wire from the starting solenoid (purple/black).<br /><br />Resistor wire ... no harm in replacing it. Just make sure you use wire with the same resistance per foot. The only thing you don't want is weak spark (higher resistance wire) or fried coil (lower resistance wire).<br /><br />Where to get resistor wire ... they always say to use only marine grade wires since automotive insulation won't withstand the moisture, heat and salt for long. I myself replaced my engine wires with marine grade. Yes, it is expensive but just for the piece of mind.<br /><br />While you're at it, you might really want to replace also the resistor bypass wire (runs along the resistor wire). You will save yourself a lot of trouble in the future.<br /><br />Hope this helps.<br />Lou

 

[Liv2fish2]

Re: OMC Cobra Ignition - No spark from ignition coil

Thanks for the additional advice, Lou. I successfully got the engine running last night and it now runs better than it ever has. It was a combination of a corroded ignition coil and the condenser wire shorting to ground. The condenser wire in the distributor rebuild kit was too long and would get hit by the rotor and push against the casing and ground. Clipping the wire shorter and installing a new connector help solve this. Before final adjustments were made on the distributor, I decided to compare the voltages of the old coil and new coil (swapping back and forth). The voltage difference was like night & day. Bad coil. At $150 for all the replacement parts, I would definitely recommend this be done every couple of seasons if you live in a moist climate like myself. In addition, I went with some new Bosch platnum spark plugs and the whole engine seems to run cooler and more efficient. I ran it for 20 minutes last night while flushing the cooling system and it was only warm to the touch - even in 65 degree weather. Now to concentrate on the regular maintenance issues!

 

[Redsfilthy]

Re: OMC Cobra Ignition - No spark from ignition coil

If you want reliability, I would order an electronic ignition conversion kit from Pertronix.One summer I chased problems from a momentary bog at take off to a high speed miss.I replaced my points with this kit and my boat runs the best it ever has. Best of all you can still run it with resistor wire.You also don't have to remove the distributor.

 

[hammerfist]

Re: OMC Cobra Ignition - No spark from ignition coil

similar issues here, i cant seem to find the ignition swap kit for my omc ford 2.3l, cobra o/d here on iboats, would love to change these points out! any tips? thank you in advance...

 

[bruceb58]

Re: OMC Cobra Ignition - No spark from ignition coil

You should start a new post instead of responding to the end of a 7 year old one. You will get more replies that way.