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Engine stalls shifting into forward

amking75

New member
Alpha 1 Gen 2
Mercruiser 4.3LX

Engine stalls when I shift to forward gear.

Went through cable adjustment procedure. Lower cable is right on 6” centers. Measured cable play at ~1/4”.

If I adjust upper cable 4 turns out per spec, the lower cable extends to ~6-1/4” with the shift assist installed.

Am I doing something wrong on the adjustment?

Thanks
 
1. was it stalling when shifting into forward gear before you adjusted anything?

2. Cable play at 1/4" doesn't mean anything. There is NO spec for that.



Based on answer to number 1 will determine next steps.

Also how about some accurate history on boat and on shifting issues like when they started and if there were any over heating issues prior to shifting issue.

When was outdrive serviced last? Who did it, You or a professional?


DETAILS DETAILS....

Here are MY shift cable adjustments and measurements.

[FONT=&quot]Trim outdrive up 1 inch of trim ram extensio from all the way down.

Take keys out of ignition!!!!!!!!!!!

Have a second person stand at the prop.
You, remove the short shift cable from the shift bracket. The one that goes to the outdrive.
After the cable has been removed, push the plastic cable end all the way in and hold in place while prop is being spun C’Clockwise..
Have second person rotate prop counter clock wise until the prop is fully engaged and wont turn anymore. Maintain light effort on shift cable plastic end pushing it to keep forward engaged.

Measure the distance from the center of the brass trunion/barrel to the center of the round mounting hole in the plastic end. Adjust trunion to make that distance 6 inches. no more no less!

Put shift control handle in forward FULL throttle position.
Remove the control shift cable (upper) from shift bracket at this time.

Install short shift cable back onto bracket at this time.

Take the shift control cable and adjust the trunion so it fits perfectly back into the shift bracket.
Before completely installing it turn the brass trunion 4 complete turns away from the plastic end and reinstall into shift bracket and install the nuts but do not tighten at this time.

Now put shift control handle in the neutral position.
Have second person spin prop, it should spin freely.
Put shift control into the forward detent position at ~ 10:00 position. NO FURTHER.
Have the second person rotate the prop counter clockwise. You should have solid engagement with no ability to continue to turn the prop.

Now shift back into neutral. Prop should spin freely with no clacking or clunking.

Now shift to reverse to the 2:00 o’clock detent position NO FURTHER!!

Have the second person spin the prop clockwise.

If you have positive engagement with no clunking or jumping out of engagement, you are done.

If it does not fully engage into reverse than look at the shift bracket where the short shift cable mounts and there is a slot. Loosen the 7/16 hex that is touching the bracket and move the stud so you are pulling the short cable. [/FONT]

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[FONT=&quot]If this all works then tighten all nuts down making sure the cable ends move freely and the nuts are not tight against the shift cable ends. The studs must spin freely inside the cable ends.

Try this and retest in water under load.[/FONT]
[FONT=&quot]If the stalling when shifting into forward or reverse still occurs then you may need a short shift cable replacement or the shift linkage in the bell housing has issues. Either way the outdrive will have to come off. The short shift cable should move very easily. If you feel a lot of resistance that typically means the cable is bad. The shift interrupter switch is activated when the short cable feels resistance when trying to come OUT of gear only under normal operation while running in the water. [/FONT]

[FONT=&quot]So if the resistance is present when shifting into gear the interrupter switch will be activated and it should not be. Again this could be short cabkle or shift linkage at bell housing[/FONT]

[FONT=&quot] [/FONT]
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[FONT=&quot] [/FONT]
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Anyway there are tests that would tell you if the cable is bad but to difficult to type out here but in general if you remove the shift control cable from the shift bracket, shift the control handle to full forward/wide open throttle and make a mark on the cable end, now go full reverse and repeat. Measure distance between marks, (2 7/8" to 3 1/8") anymore and replace the control cable.

Short cable measurement test,


Remove short cable from shift bracket, push all the way in and spin prop by hand C’clock wise until full forward is made. After it is in forward gear, with person holding prop in gear you pull very lightly until light resistance is felt, then make mark 1 on steel threaded tube at end of plastic connector.

Pull cable for reverse, spin prop clockwise, person holds prop.
Push cable very lightly until light resistance is felt the make mark 2 on threaded tube at end of plastic connector..

Measure between marks.


The measurement should be, if I remember correctly 1/2 " to 9/16". Anymore and the cable or linkage is bad.
 
1. was it stalling when shifting into forward gear before you adjusted anything?
No. On first test run of boat it would go into forward but apply throttle right away and "jump" forward. I tried to adjust the throttle cable at the carb, but that created the stall issue. That was undone and the stall issue remains with grinding as it goes into forward (only).

Also how about some accurate history on boat and on shifting issues like when they started and if there were any over heating issues prior to shifting issue.
When was outdrive serviced last? Who did it, You or a professional?
DETAILS DETAILS....

Rebuilt motor installed in boat within the last month.
I replaced the outdrive impeller while it was off for the motor work.
No overheating issues during the 2 previous summers but based on the disintegrated flappers in the y-pipe during engine work, possible overheating in the past.
No previous stalling issues when shifting. It would grind gears at times.

Here are MY shift cable adjustments and measurements.......
Put shift control into the forward detent position at ~ 10:00 position. NO FURTHER.
Have the second person rotate the prop counter clockwise. You should have solid engagement with no ability to continue to turn the prop.


After following the adjustment steps, the gears click with lever at 10 o'clock and rotating CCW. Neutral is good. Reverse is good.

Thanks for your help!
 
On the shift bracket where control cable and short cable attach.
The short cable end, it is attached to a stud in a slot.

Loosen the hex under cable end and adjust. Move 1/4" towards pivot side of arm.
This should cause more forward engagement.

If this works and you now lose reverse, most likely the short shift cable is worn internally and needs replacement.

Were you able to perform the measurement test I mentioned?

It is a bit difficult for a novice but if you can do it correctly it reveals if the short cable is stretched/worn
 
On the shift bracket where control cable and short cable attach.
The short cable end, it is attached to a stud in a slot.

Loosen the hex under cable end and adjust. Move 1/4" towards pivot side of arm.
This should cause more forward engagement.
Moved the stud lower 1/4" to bottom of slot. No change at 10 o'clock position. Still doesn't engage.

Were you able to perform the measurement test I mentioned?
It is a bit difficult for a novice but if you can do it correctly it reveals if the short cable is stretched/worn
I attempted this measurement. Push cable in until CCW locked. Marked threads. Pull cable out until CW locked. Push in until felt resistance. Measure over 1" between marks.

Looks like a new cable is in order?

Thanks
 
That measurement is tough. When I say resistance i mean,
Using two finger tips lightly pull or push until very very light resistance is felt and make marks.

If you push cable end all the way by hand you get forward, correct?


Also you really should remove drive and look at all the shift linkage.
There is a bell crank with a small wheel and that needs to be viewed to see if the whell is intact.
 
If you push cable end all the way by hand you get forward, correct?

Yes.

Also you really should remove drive and look at all the shift linkage.
There is a bell crank with a small wheel and that needs to be viewed to see if the wheel is intact.

Are you referring to the wheel that fits into the shift cable slide in the gimbal housing?

I will get the drive pulled. Needs to come off either way at this point.

Thanks
 
Pulled the drive tonight. Pics attached. Thanks
 

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Not what I meant

The wheel is round, the surface is flat.

What I meant was are there any flat spots from wear...

It looks ok not that you cleaned the grease off it.

The shift cable end that the wheel fits into,
How much end play is there.. This is felt by lightly pushing and pulling cable end. There should be NO end play but the cable end should be able to rotate freely.

The set screw is used to adjust.

If all of this is Good then the issue is most likely the cable but we may need to discuss over the phone. Too much to discuss by typing.

If you private message me your phone number and a time to call EST I will give you a call to help nail down the issue
 
Not what I meant

The wheel is round, the surface is flat.

What I meant was are there any flat spots from wear...
No detectable flat spots on the wheel or wear in the lever.

The shift cable end that the wheel fits into,
How much end play is there.. This is felt by lightly pushing and pulling cable end. There should be NO end play but the cable end should be able to rotate freely.

The set screw is used to adjust.

If I push/pull lightly on the shift lever attached to the cable there is some play. Maybe 1/16" or so. It is enough to be noticeable.
 
There should be NO movement, The set screw should be just loose enough to allow cable end to rotate freely.

Every 1/16" of excess movement adds up and makes adjustment of the shift cable more difficult.

The difficult measurement test I asked you to do with a spec of 1/2-9/16" max is on;y 1/16"

if you can, adjust set screw to remove slack and put drive back on and see if it is enough to allow forward gear engagement.

Even if this works, it may not last as I still believe cable is worn and is the most likely cause of your issue at this point
 
Is this the proper routing for the lower shift cable?
IMG_0575.JPG
I was looking at my existing cable routing and it comes through the transom and behind the y-pipe.
It's possible I moved it out of the way when the engine was out this spring. I did have to remove the y-pipe to retrieve pieces of the exhaust flappers.

Thanks
 
Just like the picture,
Whats missing in the pic is the engine block.

Its a tight sqeeze but if you do not route it that way, the cable will rub on the coupler and you will be replacing it again.
 
Simply for testing purposes
remove the control cable
adjust barrel to 6 inches,shift lower cable into full fwd ,prop locked CCW
put control box in full fwd
adjust control barrel to fit
test shifting
 
I don't know if this helps but 4.3 merc was stalling when reverse was engaged
on the cable mount there is a brass type little rod was the problem ..
with a little bend problem was fixed
i do not recall if it was threaded ..but this is more than likely the culprit ..
check for proper way to adjust and it has direct conection with cut off switch for motor and will stop motor from running ..
good luck
 
I’m late in posting an update …

I replaced the lower shift cable. After following all of the advice above, I noticed that the lower shift cable was routed incorrectly causing it to bind during operation.

The incorrect routing was my fault and happened while the motor was out for repair earlier this spring. In an effort to move things out of the way, I inadvertently pinched the shift cable between the y-pipe and the transom.

As a novice, I would recommend following some of the YouTube videos showing this process. I found the SEI Marine video to be the most thorough. If my cable had been routed correctly, using a piece of wire as a snake would have made the process a lot easier.

Thanks for all the help on this issue!
 
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