Mercruiser Shift Interrupt Switch

[transcorpiboats]

I have a 1982 Merc 350 V8 260hp w/ Alpha One I/O

I've developed an inconsistent shift issue that i suspect is a faulty shift interrupt switch.

Here's what's happening...

When in idle and shift into forward gear, sometimes it will shift perfectly, then the next time it kill the engine. There is no set pattern. Same for reverse.
I don't believe I have a cable that might be binding or need adjusting but I could be wrong. On 1982 equipment anything can happen I guess.

Question - does the fact that this is an inconsistent issue suggest that it might be the switch acting up?

 

[ahicks]

That's the first thing that came to my mind - switch sticking.

 

[Chris1956]

Check the lower shift cable for binding. They are (obviously) more susceptible to corrosion.

 

[mr 88]

^^^ The shift interrupter should only work/move when shifting into neutral from either gear. It is not supposed to interrupt when shifting into forward or reverse. You could always disarm it if your idle is set low enough and see if it makes a difference,the only thing though is you said it did it randomly.

 

[Mischief Managed]

You have a sticking lower shift cable. The shift interrupt switch can only activate when there's excessive tension or pressure between the upper cable and the lower cable. They rarely fail and the fact that your engine runs then stalls means the interrupt switch works perfectly.

 

[Lowlysubaruguy]

Mine needs adjusted every x number of years theres a proceedure on line i figure out what tools i need and head to the water tinker with it until its just right.

 

[QBhoy]

As above or/and idle speed adjustment required.

 

[QBhoy]

Or you're still tied up to the dock...haha.

 

[Bondo]

I don't believe I have a cable that might be binding or need adjusting but I could be wrong.

Ayuh,... Welcome Aboard,... You are wrong, ya need a new lower shift cable,...

The shift switch should only move when comin' outa gear, in the water,.....

Yer symptoms scream bindin' lower cable,....