Help help!! 1999 mercury black max 150 keeps stalling when it goes in gear..

Ok i just bought this boat a week ago and the motor seem to run fine i put a knew prop on yesterday. How ever now the motor stalls when it goes into gear.

Typically caused by a blockage in the fuel system (can't supply enough under load when it calls for a greater fuel volume).

If it's a carb model, clean the carbs and rebuild if you find toasted parts.

If injected they may be clogged.

You may need to test the fuel flow (output).

Check for air leaks in the fuel line, restricted pick-up in the tank, lack of tank ventilation etc.

Sorry, could be many things "fuel related" - can't give you a "do this and it's fixed" in this case.

Grab a manual and start troubleshooting or take it in to have it looked at...

Make sure all cylinders are getting spark! It may idle fine, but when put into gear without all cylinders firing, it's not enough power!!

is it the right prop.same diameter and pitch as last one.How was it running with old prop.when in gear what was idle speed on tach.sounds like idle needs to be raised slightly then trouble shoot from there!