Shift cut out/starter lockout

[Ncherry84]

So now that I have my ignition issue put to rest finally, I raced home from work the other night and grabbed the boat and dipped it in the lake. Really late in the season here and crumbly weather so I'm able to have the launch to myself...so I kept the boat on the trailer and backed it in to submerge the gimbal housing and sterndrive.

Anyways, fired up the motor, set the timing (8* BTDC) and set the carb pretty close, found a couple minor water leaks from me being cheap that are easily rectified. Motor warmed right up to 170 and purred like a kitten with little to no hesitation with quick throttle snaps in neutral. Went to set the in gear idle and fun stuff like that, my shift interrupter is killing the engine when I try to put it in forward or reverse. My seloc book doesn't have real great coverage of the interrupter that I could find. I'm thinking i might have it wired up wrong....but obviously works kinda right because I can't crank the boat at all in gear.

Does anyone have a good wiring diagram for the switch? I'd rather not bypass it if I don't have to.

Thanks!

 

[alldodge]

Its a Mercruiser what?

 

[Ncherry84]

Its a Mercruiser what?

My bad....4.3lx 0d836623

 

[Bt Doctur]

my shift interrupter is killing the engine when I try to put it in forward or reverse. My seloc book , you mean your knee pad?

If the switch is activating going into gear you need to check/replace the lower shift cable or find out why the mechanism is sticking/corroded. The shift interlock to prevent starting in gear is in the control box

 

[alldodge]

Agree lower shift cable is probably causing the issue

You have a TB4 so interrupt uses a ground

 

[Ncherry84]

I'll give the lower cable a shake down tonight after work and see what's brewing there. Just looking for corrosion and sticking?

 

[alldodge]

It has to much slop (cable wear inside the cover) in it so the interrupter gets stuck in the engaged position

 

[achris]

Going into gear, the switch activation lever shouldn't move at all. You have a sticky (not worn) cable or something stuck or tight in the shift system beyond the cable. Pull the drive and start assessing everything in the shift path.

Chris.......

 

[Ncherry84]

Going into gear, the switch activation lever shouldn't move at all. You have a sticky (not worn) cable or something stuck or tight in the shift system beyond the cable. Pull the drive and start assessing everything in the shift path.

Chris.......

I'll start at the front and work my way back....but I feel its probably in the drive itself. I don't know what it's called but in the bellhousing at about 4 o'clock there was a block/rod screw looking thing that I bumped and not sure how it was positioned and I kinda guessed I think when I put the drive back on.....but start at the front and work my way back.

 

[QBhoy]

Hi
as far as I know the shift interrupt shouldn’t affect it going into forward gear.
Also might add that you mayne should avoid setting up timing in neutral on the trailer. Pretty sure you should be warmed up at least and maybe even in gear at idle. Someone will confirm or ridicule me soon, haha.

 

[achris]

I'll start at the front and work my way back....but I feel its probably in the drive itself. I don't know what it's called but in the bellhousing at about 4 o'clock there was a block/rod screw looking thing that I bumped and not sure how it was positioned and I kinda guessed I think when I put the drive back on.....but start at the front and work my way back.

I think you're referring to the shift slide (# 31 on the bottom drawing), and the upper shift shaft lever (#25 on the top drawing). There's also a seal that shaft goes through that's inside the exhaust cavity (#6 on the top drawing). Those burn out and need to be changed. Once water gets in, it sets up corrosion which tightens around the shaft, adding load to the cable, causing the cutout to operate when it shouldn't.

The slide on the end of the cable needs to be able to rotate, without being TOO loose. Check that.. Sometimes when trying to put the drive back on, that slide will rotate and the roller in the lever will move out of alignment. You need to make sure that doesn't happen!

Chris...

Here's some diagrams with all the part names... For reference ...

 

[Ncherry84]

Hi
as far as I know the shift interrupt shouldn’t affect it going into forward gear.
Also might add that you mayne should avoid setting up timing in neutral on the trailer. Pretty sure you should be warmed up at least and maybe even in gear at idle. Someone will confirm or ridicule me soon, haha.

It was in the lake, on the trailer. I didnt do anything with the timing until it was warmed up to 170 degrees on the gauge and running stable with the choke opened up. I wasn't running on muffs at all. I was looking to set in gear idle when I came across this issue.

Chris, thanks for the parts diagrams and now I finally know what the part was I'm talking about! Im about 90% sure it's the shift slide....but now I'm wondering what the correct orientation would be for it when the drive is in forward and removed? Work the last few days since making this post has been a disaster so I'm finally now circling back to working on this.....today after doggo goes to the groomer I'm gonna look over these things and muff it to warm up the oil to change out the first run oil and filter before winter sets. I may not have to do that.....but practice for me with motor swaps has always been run for an hour on new oil and filter then drain and replace then start the break in cycle. Clean out the crap that got in the motor while sitting open, plus assembly lube, etc.