Stalling when I try to throttle up

[Jimmy Queensland]

Hey guys looking for advice please .
I’ve got a 1999 30hp 2stroke mariner. Recently had it in a boat shop for service and tune up. When I got it back I put a new stainless steel performance prop on it because the old prop was quite worn down.
Took it for the first run today and was running beautifully for the first 10 minutes then died .
Would start first pull and rev fine in neutral or reverse but in forward I can’t go much over idle without it dying .
I’m in no way mechanically minded but think maybe the bigger prop needs different adjustments on the carburettor.
Fuel lines were all replaced and a water separator was installed while in the shop so I’m sure it’s not a fuel line problem.
Any ideas greatly appreciated I’m going back out tomorrow to play with it on the water

 

[R_P]

Sounds like a dirty carburetor or old gas/water in fuel situation

 

[racerone]

Open low speed mixture screw 1/4 turn and test run.

 

[Jimmy Queensland]

Sounds like a dirty carburetor or old gas/water in fuel situation

Carby had clean and kit done but some of the fuel in tank is couple months old. Might be that. I normally fill the tank with fresh fuel if it’s been sitting for a while, always thought if there’s more fresh than old it will be ok?

 

[Jimmy Queensland]

Open low speed mixture screw 1/4 turn and test run.

I’ll have to google which screw that is and try it, thanx for the advice