Alpha one not shifting right under load

[Fordon40]

I have a mercruiser 170 alpha one outdrive. It shifts fine on the trailer motor on or off. Put it in the water and have reverse fine but to put it in forward gear you have to throttle it a few times until there is an audible thud and then it will throw everyone/everything forward. All the cables have been replaced several times, adjustents done countless times, shift shaft replaced. Any ideas as to what else it could be? I am thinking the shift spool but can not find much about it.

 

[thumpar]

You could try to disconnect the lower shift cable at the engine and manually shift to see if it works then.

 

[alldodge]

Has your throttle handle been replaced or just the cables?

 

[Fordon40]

Both the throttle cables and handle have been replaced. The cable moves smooth and with move at the motor but once it's in the water starts acting up but not when it's on the trailer

 

[alldodge]

My thought behind asking for the handle is the Merc needs a certain distance of travel to shift. If the throw is not long enough it will not shift correctly. Going to need to look it up to see what it is and will advise.

What model and manufacture handle did you get?

 

[alldodge]

Shift cable must move 3 inches =/- 1/8 (2 7/8 to 3 1/8)
Checking Remote Control Shift Cable Output
IMPORTANT: Remote control must provide a shift cable travel (at the shift plate end) of 2-7/8 in.
(73 mm) to 3-1/8 in. (80 mm) with a 15 - 20 lb. (6.8 - 9 kg) load applied to the cable end guide.
Models with Shift Assist: This measurement can be taken by installing the remote control shift cable
and using the shift assist assembly (provided) to place the proper load on the shift cable (drive unit
shift cable should not be installed).
Models without Shift Assist: This measurement can be taken by lightly pushing and pulling on the remote
control shift cable end guide, to place the proper load [15 - 20 lb. (6.8 - 9 kg)] on the shift cable.
1. Place remote control into gear as follows:
Right Hand Rotation Drive Unit - forward gear wide-open-throttle position.
Left Hand Rotation Drive Unit - reverse gear wide-open-throttle position.
Place a mark on threaded tube against edge of cable end guide.