Mercury 9.9hp throttle cam adjustment

[Paroo2020]

Hi
When I went to go in reverse on my outboard the engine revved before going into reverse (rather dangerous) I have inspected the throttle linkage and finally realized that the throttle cam is out of position relative to the neutral position cam



Can anyone assist with information on the correct method and information on how to adjust the position of the throttle cam relative to the neutral position for my 9.9hp Mercury outboard.


The cam has a bolt on the middle and I suspect if I loosen this then I can adjust the position relative to the neutral position cam. However I don't want to do this without confirmation first.



Thanks for any assistance or information.
Tony

[GordMay]

Mercury 6/8/9.9/10/15 HP 2-Stroke Service Manual
➥ http://www.baads.org/wp-cms/wp-conte...nual_PART1.pdf

[Paroo2020]

Hi
Thanks for the manual -I think I would need section 7 to fix this issue.


Kind regards
Tony

[Nicholson58]

Thanks Gordon.

ALSO!

We have two older model Mercury OBs with tiller controls. 9,9 and 15 HP. What we learned:
The cover on the two tiller cables cracks and lets in (salt) water. As the Bendex coils corrode the apparent length of the sheath shortens. The inner cable become slack and the take up adjustment is insufficient. Replace the entire cable assembly. About $80 on line.
The rotating bell crank bits have too much hysteresis either from assembly or wear. I fashioned a plastic bushing for one, a bronze bushing for the other. The stack on the pivot bolt is too loose also. I added SS shim washers to make this near zero slack. Note the SS washer in the photo.

These two physical improvements and the manual restored excellent action and control.

Other Merc improvements:
Change the aluminum prop to SS Solas. (Picture) About $70 on line. Consider the use. We needed to reduce the pitch 1” for the RIB with two people and groceries.
Own a spare water pump kit. The entire kit is way less than the parts.
Buy a spare zinc. Also, we added an aluminum whale tail plate with a large extra zinc. (Picture)
There is a tiny thermostat on the cooling housing above the plugs. Get a spare. (Picture old one)
Have at least one spare primer pump rebuild kit. Ethanol ruins these.
Add a transom filter on the dinghy with a water separation bowl. (Photo)

[GordMay]

Originally Posted by Paroo2020

Hi
Thanks for the manual -I think I would need section 7 to fix this issue.
Kind regards
Tony

I’m sorry; I didn’t note that the manual was in 2 parts.
Merc’ Service Manual: Part 2 ➥ http://www.baads.org/wp-cms/wp-conte...nual_PART2.pdf

[Paroo2020]

Hi Gordon
Thanks for part 2. They have changed the design slightly on the newer model but I managed to sort it out.
The throttle cam had somehow manager to slip a couple of notches so that in forward there was a lot of movement before acceleration and in reverse it was the opposite.
Re aligning the cam position so the neutral spot had throttle play in forward and reverse gears solved the problem.


Kind regards
Tony

[GordMay]

Tony:
Thanks, for updating, with the resolution.
Too few do.