Re: 15 hp mercury need heeelllppppppp
Here is a list of ideas That I can think of to ask your self if you have done any of these things yet as a starting point.
Have you checked for spark yet???
Have you pulled out the choke yet???
Did you open the vent on the fuel tank yet???
Did you make sure the lanyard safty switch was 100% up and in the run position???
It's in neutral?
Did you press the fuel primer 2 tiems and pull out the choke/Fast idle knob for starting. Note if the engine has been sitting for a long time the primer lines may have air in them. In this case , Depress the fuel primer ten times rapidly. [All this is in the book]
Flooded engine, If the engine will not start, Push the throttle only button and advance the throttle grip to fast throttle speed . Push the choke knob and retry starting the engine.
Is the primer bulb getting firm while you tried forcing some fuel into the filter and looking for fuel leaks at the filter connections, ect?
Spark plug gap is [0.035in]?
Oil is not over full???
The fuel is 100% new from the tank to the carb??? If you where using old fuel then that would not help, But since you have new "ethonl" fuel in it, That should not be a problem.
Have you checked the engine compression at all with either a gauge or put your finger in the spark plug holes just to see???
Did you play with any of the idle or air/fuel mixture adjustments on the carb and get them out of adjustment???
Make sure the engine stop switch "button" at the end of the tiller handle is not stuck in or "pushed in" I should say.
While in storage did the engine ever lay down on the ground on it's side??? There is only a certain way you can lay it down on the ground or oil could get inside certain areas and flood the engine??? Pull the plugs and crank the engine over a few times just to see what come out.
I'm sure I missed something here can anyone add to this list please, Thanks.

Hope this helps some good luck with it.