OMC 4.3L Cobra, Ignition Problems over 2500RPM

[searay3]

Usually 'checking' the points/cond,cap,rotor plugs doesn't tell you much. replace these items, check/change fuel filters, water seperator, anti siphon......a full tune up. After setting timing and adjusting carb, post back with results. If you did a search, there is a multitude of different failures that cause this issue. You have to be absolutley sure the basics are in order and then can go on doing compression tests, fuel tests, coil and other things.

 

[rogerrabbit81]

Re: OMC 4.3L Cobra, Ignition Problems over 2500RPM

Replaced the plugs & water separator filter again. Points, Condenser, etc were replaced very recently - less then 5 hours ago. I was thinking replaceing the coil.

 

[searay3]

Re: OMC 4.3L Cobra, Ignition Problems over 2500RPM

Just so happens I had the same power issue. Hit a rock in a lake in South Dakota. Right after that, no power after 2500 rpm. (87 merc 4.3 lx sbc). Came home dissapointed and scratching my head. Replaced the coil and it ran great again. I bought an Universal Accel coil that lasted about 7 trips, started to act up again. Bought a MSD for electronic ignition and it has been as dependable as can be. Buy the coil for your system, whether it's 12 or 7 volts going to the positive terminal.

 

[rogerrabbit81]

Re: OMC 4.3L Cobra, Ignition Problems over 2500RPM

I had bumped a log in the Delaware on Satuday - coincidence? That is the last time she ran correctly. Thanks for tip and quick response. I'll give it a shot. Any thoughs on the electronic conversion? I was thinking that might help eliminate current/future problems if I remove the points setup.

 

[pra100]

Re: OMC 4.3L Cobra, Ignition Problems over 2500RPM

Look at,http://www.pertronix.com.
I got the ignitor II and love it.Simple,simple to install.But must build a little circuit to make it work right with esa on a omc cobra.The little circit is very easy to make.
Their tech.support by phone is very helpful.

 

[Boatin Bob]

Re: OMC 4.3L Cobra, Ignition Problems over 2500RPM

If you do want to go with the electronic iginition (Pertronix) there is a new style ESA module out that works with it so you don't need to build the extra circuit, here is a link for reference go2marine.com/product.do?no=90470F - CDI/Rapair OMC Module Getting back to your problem though I think the fact that hitting the trim almost kills the engine is a clue. I would suspect a power problem, bad, loose or corroded cables at the battery, switch or engine connections, sounds like your ignition is power starved. Check all main power connections.

 

[mthieme]

Re: OMC 4.3L Cobra, Ignition Problems over 2500RPM

I had a similiar issue. Those cheap Chrysler points would float after rounding the 3000rpm bend. I replaced them with the Pertronix CDI module and I now have the full rpm range. Huge HUGE H-U-G-E difference. You can still use points if you want (emergency) too.