Motor will not stop

I have a carburated 1994 225. Engine starts fine, but will not shut down when ignition is switched to off. I replaced the ignition switch with a new OEM switch. Still won't stop. Checked wiring and connections from switch to motor, all looks fine. When I turn the switch to stop, the rpms drop slightly. If I bump the thottle/shifter a few times to forward and back to neutral I can get the motor to die. Any ideas? Thanks.

Re: Motor will not stop

I am going to assume you have a 2.5 liter 225 with standard ignition.
(2 packs) It sounds like you have a bad pack. To test remove spark plug wires. Remove blk/yel wires from packs and turn key on, with omh meter put one end to engine block and other to each blk/yel wire, you should have no reading. With key off perform same test but should show reading on both blkyel wires now. If not the one with no reading is broken in engine harness. If both read right, reassemble and start engine on hose. With timing light turn key off and check port & starboard plugs. The side still firing is the bad pack, trace your coil wires from that side back to pack and replace. To kill engine disconnect fuel or hold in button on top of enrichener and this will flood engine and kill it.

Re: Motor will not stop

The ignition system has an Electronic Countol Unit. I believe the ECU performs the function (among others) of the packs you describe on the standard ignition (let me know if I'm off-base on that). If so, are there any diagnostics I can do to find out if it's a bad ECU?

Thanks for your previous response.

Re: Motor will not stop

If it has a ECU it is fuel injected and not carbed. If it has 2 packs on the starboard side of engine, test as I have posted. If not post serial # ..Thanks

Re: Motor will not stop

Cross my heart, it is carburated with an ECU. No packs on the starbord side. The SN is OG110457.

Re: Motor will not stop

Ok.. you have a 3.0 liter,different animal. See the attached picture and check the diode show as blk/yel is common to all the cdm modules and only seperated by this diode.

Re: Motor will not stop

OK, so the blk/yel is coming from the powerhead harness plug where it splits at the diode with one-half of the split feeding the starboard-side cdms and the other half feeding the port-side cdms through the diode. When I find the diode am I doing a visual check to see if it looks fried, or an ohms test on the blk/yel as described in your first email response?