125 merc 2x2 not getting on step

[jim reiss]

i have a 1997 125 merc 2x2. it will not go into the 3 and 4 cylinders. It idols fine and get up to 5 rpms but with not go to the other cylinders which of course will not get on step. any suggestions

 

[guyjg]

it will not go into the 3 and 4 cylinders....which of course will not get on step.

Not sure what the statement means. Are you saying that only one bank of two cylinders are firing and the gearbox won't shift?

 

[tonyaus]

More info needed here...
Do you mean it gets up to 5000 rpm? Is this in the water or on a hose? Hopefully not on the hose for that engines sake...
When you say step, do you mean the boat doesnt get up on a plane?

 

[Mpguth]

I am having a similar problem, my 2000 125 was only running on two and would not get on plane. Changed the plugs, installed a new filter, and added a can of Seafoam to the 6gallons of gas in the tank. Now all four will start but, it takes about a minute to get on plane, and will not exceed 3500 rpm. Does this also applies to you?

 

[guyjg]

Try another prop.