Shift Interrupter Switch

[bhuff]

Ok so last summer I bought my first boat. 92 Marada nineteen fifty. It has a 5.0 OMC Cobra. The guy I bought it from didn't know much about boats either. He told me when he bought it, it would not go into gear and it would just grind so he had the outboard rebuilt. But it would still grind. He said that a friend helped by showing him the shift interrupter switch, he unplugged it, idled the engine down real low and now it goes into gear but pops just a little when falls into gear. I decided it was time to fix that. I took the switch off and hooked a test light to it. When the button is pushed the switch flows current, so I figured it was maybe out of alignment or something. Crank the engine, and plug in the switch, nothing happens, I push the button and nothing really happens, but if I tap the switch really fast the engine starts to sputter. Is this normal? Do I really need to buy a new switch, the test light showed that is good? Could there be a problem somewhere else? I know very little about boats so any information helps.

Thanks

 

[Don S]

Re: Shift Interrupter Switch

What you need to do first, is figure out the how, what, when, and why of the shift interrupt system so you have some idea what it does, when and why. Then you may understand it a bit more and understand what the answers you get mean.
While this may be for a Mercruiser, they do the same thing for the same reasons.
Have a read . http://forums.iboats.com/showthread.php?p=1930449#post1930449

 

[bruceb58]

Re: Shift Interrupter Switch

First of all, the interrupt switch does nothing when you put the boat into gear. It also does nothing getting it out of gear unless you are in the water. When you are in the water, the force on the dog gears applied via the prop tries to hold them together. As you try to shift, the extra force being applied through the lower shift cable engages a switch connected to the ESA. This ESA is what interrupts the spark.

The first thing you need to do is make sure the drive shifts properly out of the water. They do make a grind noise as you put them into gear and that is why you want to shift swiftly into gear. That is just how they are designed. It is very possible that your shift cable is not adjusted properly. Not many people know how to properly adjust them.

You can manually test the ESA by depressing the switch connected to the ESA. if the engine stumbles, the ESA is working properly. What you then have to do is make sure the switch is adjusted properly so that when you shift OUT of gear, the switch is operated.