Thumping when accelerating

[AcogDoc]

Well.... I’m back!! Boat is running took it out for the first time since the switch boxes were fixed. I have a 1996 mercury 150 off shore on the boat (2 stroke) and when I’m accelerating I get like a thump... thump... thump.. it’s pretty noticeable and you can feel it. If you accelerate quickly it will go away and you can slow back down and everything IS fine. But it’s always the initial acceleration. It’s not like grinding from putting in forward or reverse too slow it’s not like that at all. It’s a more like thump than a grind. Any ideas what this could be??

[steplift20]

What year is your motor?
Is it carbs?
I have a 150 merc too , what I would check
Check plugs and plug wires, make sure they are in good
Change the water separator if you have one
It might be a carb problem if you have them could be a miss fire
Good luck

[AcogDoc]

1996 mercury 150 off shore 2 stroke carbs.

[spareparts]

trim the motor up and grab the lower unit, pull back and see if you get any unusual movement, if the motor mounts are shot, it will make noise like that. If it is jumping in and out of gear(feels like you hit a log), adjust your shift cables before any damage is done. When adjusting the cables do it with the engine running. Think about the shifter being a clock, neutral is 12, you want fwd in by 10, reverse somewhere around 2 o'clock, get fwd in as soon as you can, without it grinding before going in reverse. Try to keep it balanced, but if you have to favor one or the other, give fwd the bias

[AcogDoc]

Thanks spare! I’m gonna look into it. I did change the cables before this noise started happening and before the switch box dilemma. And I noticed it after I changed the cables. I swear I did everything right. I’ll check the trim business and the control cables. But if I remember correctly it’s in forward at about 10 and reverse about 2. Is there any reading material you can point me in the direction to try and make some adjustments the right way?? You’re the best man. As always thank you for your help.

[Blue_Runner]

Great advice, sounds like something might be going on there with the new cables.