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-   -   enigne cutout switch wiring (http://www.mariahownersclub.com/forum/mercury-mercruiser/4754-enigne-cutout-switch-wiring.html)

elimont 08-20-2010 04:26 PM

enigne cutout switch wiring
 
I just got a 96 Barchette 182 and am trying to get the engine to shift correctly. The marina guy said its the wire coming from the cutout switch and I should be able to fix no problem. He was wrong. The wire that goes to the distributor is not hooked to anything. There are 2 plugs on the distributor one has wires runing back into the harness the other has 4 wires with nothing hooked to them (purple/white, white, tan/black, black/red) none of these match the wire color from the switch white/green. Has someone put an automotive distributor in and they are not the same ( it is new ).

Sorry me explinations are so long. And thank you for the help.

BTW love the boat and only had in water for 1hr. Looks good on trailer rolling from FL to VA.

mikeyt 08-20-2010 06:34 PM

Re: enigne cutout switch wiring
 
Quote:

Originally Posted by elimont (Post 25176)
I just got a 96 Barchette 182 and am trying to get the engine to shift correctly. The marina guy said its the wire coming from the cutout switch and I should be able to fix no problem. He was wrong. The wire that goes to the distributor is not hooked to anything. There are 2 plugs on the distributor one has wires runing back into the harness the other has 4 wires with nothing hooked to them (purple/white, white, tan/black, black/red) none of these match the wire color from the switch white/green. Has someone put an automotive distributor in and they are not the same ( it is new ).

Sorry me explinations are so long. And thank you for the help.

BTW love the boat and only had in water for 1hr. Looks good on trailer rolling from FL to VA.

I've never had this problem but here's a good diagnostic reference on the interrupter switch & shift cable adjuster. Hopefully it will help out.

mikeyt 08-20-2010 06:42 PM

Re: enigne cutout switch wiring
 
Here's a good instructional post on the shift interrupter switch & how it works from our friends at iboats:

:
Usually in the spring and summer we get a lot of posts regarding the shift system for the Alpha and pre Alpha drives. Also a lot of wrong ideas on how and why the system works and why it's there. Maybe this will help explain how it actually works and why it's needed.

The ONLY purpose of the shift interrupt system in the Mercruiser Alpha style outdrives is to get the drive out of gear (forward or reverse) when the engine is running and the boat is in the water with a load on the prop. The lower gears (Both Forward and reverse) have a dog type clutch. These dogs are reverse cut so they try to hold themselves into gear, and will stay in gear even under heavy load. Even at idle they are under a fair amount of load and without the shift interrupt system, it’s almost impossible to get out of gear. You can see the undercut and how the shift dog fits in the gears in the picture below.

What happens with the shift interrupt system when moving the shifter from Fwd, or Rev back to the Neutral position goes something like this.

When you start moving the shifter into neutral there is resistance from the engaged shift dogs that prevents them from coming out of gear. The outer sheath of the lower shift cable is attracted to the Y shaped spring loaded bracket that operates the shift interrupt switch. When this Y plate moves and activates the shift interrupt switch, the ignition coil is grounded and the engine starts to die due to lack of spark, and pressure on the shift dog is released. With no pressure on the shift dogs, the inner cable then pulls the drive easily into neutral. When this happens, the Y plate releases the shift interrupt switch and ignition is returned and the engine keeps running.
All this only takes a split second, but if you listen, you can hear the engine drop a few rpm before running normal again when coming out of gear.

With an old, corroded lower shift cable, the cable will not allow the Y plate to release and the shift interrupt switch remains engaged. Since the shift interrupt switch remains engaged for a long period of time which keeps the ignition system grounded out, the engine dies completely.

The system is NOT designed to work when putting the drive into gear, or when the boat is out of the water and on muffs. Without the load on the prop, there is not enough resistance on the shift dogs in the lower unit to cause resistance to the shift cable and engage the shift interrupt system.

The above describes a Mercruiser setup, but the OMC system with the ESA module works basically the same. The difference is the ESA module only stops spark to half the cylinders and will cause the engine to miss, which releases the pressure on the shift dogs

elimont 08-20-2010 09:40 PM

Re: enigne cutout switch wiring
 
The boat was having a hard time shifting and required way too much force to move into reverse or back into drive when it was in the water. The first page you linked to is what started my looking into this problem more. Without the wire hooked up it can not ground out the spark. I first thought this was the problem and is a problem that I need to fix. But upon looking more and reading on the Dolphinmarine page and others I unhooked the lower cable and tried to move it by hand. I am unable to move the cable at all. The shutoff switch is part of that problem but now that the cable does not move when unhooked I will probably be looking deeper. No time is better to learn about a boat than when I just want to take it out. I guess its time to follow that cable and see where it goes and if something at the end is bent, broken or rusted. I have followed it as far as it goes into the housing. I now need to replace the bellow as it was ripped and someone rather than fixing it just gooped tons of sealant around it.

This boat was looked over by a mechanic at a marina before I purchased it. Its a shame he was incompetent but now its my turn to learn.


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