OMC 4.3L starter stays engaged after engine started

[MannyTC]

I have a strange issue I hope you guys can help with. Boat is a '95 Four Winns Freedom 170 with OMC 4.3L Stern Drive

When I went to use my boat last weekend the starter re-engaged a second or two after the engine started. Turning the ignition key to the off position did nothing. The engine and starter stayed on. Pulling the emergency cutoff also did nothing. I was able to turn off the engine by removing the relay on the left side front of engine. This relay appears to be wired to the starter position of the ignition.

We have so far replaced the ignition switch, relay and starter with no positive results. Since the starter seems to re-engage a second or two after the engine starts I figured it must be somehow getting power to it again when the alternator engages.

To test this we removed the alternator belt and started the engine up. The engine started fine and the starter did not re-engage. We were also able to turn off the engine with the ignition key as expected.

Suspecting the alternator was having a problem we removed it and took it to an alternator shop which said there was a problem with the regulator. We had the unit rebuilt and re-installed it today only to have the same problem.

I don't have a service manual for this engine handy and am out of ideas at the moment. The alternator has more stuff wired to it than I expect to normally see on an alternator and am having a hard time understanding why the starter would re-engage when the alternator starts producing power.

Here is how my alternator is wired up. It is a Mando 55A with a total of 6 terminals on it.
Terminal E = Black Wire
Terminal B = Large gauge Orange Wire
Terminal S= Purple wire and red jumper that goes to the Exc Terminal
Termina Exc = Red wire which jumpers to Terminal S
Terminal L2 = Green Wire
Terminal P = small Purple wire

The wire from Terminal S has continuity to a purple wire on the starter solenoid.

If anyone can help I would appreciate the assistance.

 

[CharlieB]

Re: OMC 4.3L starter stays engaged after engine started

??????
Purple wire on the starter?????
OMC and Merc use yellow w/red trace for the starter trigger
Purple is switched 'on' with the ignition
usually to arm the ignition system and/or trigger the alt to charge


Has someone worked on this boat immediately prior to this problem?

 

[MannyTC]

Re: OMC 4.3L starter stays engaged after engine started

Well there is always the possibility that my son did something and tried to fix an issue without me knowing

Anyway I do have a purple wire on the starter solenoid on terminal D as shown on the same picture of a solenoid in this thread: http://forums.iboats.com/showthread.php?t=167035

Should that wire not be there? I found on another forum someone asking about starter solenoid wiring and they have a purple wire on the solenoid just like I do. That post is here: http://www.boatengine.net/t/052019.html.

The purple wire at the solenoid has continuity to the S terminal on the alternator as well as to the ON position terminal on the ignition switch. The purple wire looks to belong to something by the solenoid since it is wrapped up with the other wires that come down from the front of the engine. Where would that purple wire go?

Thanks for the help.

 

[Dakota47]

Re: OMC 4.3L starter stays engaged after engine started

Manny, it may be the Key switch, they get corroted and bad connections.. check it out..

 

[Coors]

Re: OMC 4.3L starter stays engaged after engine started

http://forums.iboats.com/showthread.php?t=167035

 

[MannyTC]

Re: OMC 4.3L starter stays engaged after engine started

Already put in a new ignition switch. As I stated in the original post we already replaced the ignition switch, starter relay, starter and alternator.

 

[MikDee]

Re: OMC 4.3L starter stays engaged after engine started

Ok, the bottom line is for some reason the (solenoid on the starter) is engaging (staying on after your motor starts). Basically, all that solenoid does is magnetically engage the starter drive when you turn the key to crank, or "Start",,,, Turning back to ignition on, or "Run", (after your motor starts) there should be no power going to that solenoid (check your wiring again) if you have a test light, or meter, the little terminal on your starter solenoid should not show power with the ignition on "Run". (test between that terminal and a ground source).

 

[MannyTC]

Re: OMC 4.3L starter stays engaged after engine started

Thanks for all your advice so far.

I do want to reiterate that when the starter re-engages I cannot turn off the engine with the ignition switch. That part is also kind of strange to me. I think there must be a short of some kind somewhere.

 

[MannyTC]

Re: OMC 4.3L starter stays engaged after engine started

OK guys, I have two more questions related to the purple wire on the starter solenoid.

I got a hold of a Seloc repair manual. The '95 engine wiring diagram shows only the yellow/red wire on the solenoid and no purple wire. The rest of the diagram appears to be exactly what is in my boat. The '94 diagram does show a purple wire on the starter but the rest of the wiring doesn't match my engine.

So in light of this info; should I or shouldn't I have the purple wire hooked to the solenoid.

Also I see that there should be a diodes by the fuel pump relay according to the diagram. This I presume is to stop the power from flowing back to the starter relay. I think maybe my problem with the starter re-enaging is that the diodes are leaking or have since been removed by someone.

Anxious to see what you guys think.

 

[MannyTC]

Re: OMC 4.3L starter stays engaged after engine started

Ok problem resolved.

The issue was that a diode on the line going from the fuel pump relay trigger to the starter relay trigger was leaky. Replaced the diode and the starter stopped engaging and works as normal again. While fixing this issue we also found that the fuel pump was not working properly after the engine was running. Turns out that the wire that drives the fuel pump relay after the engine starts also has a diode on it and that diode was blown completely and not letting power flow in either direction. Replaced that one too and now everything is fine again.

I am guessing the diodes got fried due to the regulator in the alternator having problems.

Oh, and I left the purple wire on the starter solenoid as it was originally.