18 hp Murray I replaced battery & regulator works better but still having issues. When you turn the key over it takes a long time to start.. 10-15 seconds? Any ideals?

There is a long list of reasons a, engine would fire up, many are carb related. Have someone spray starter fluid into the air intake when you first trun the key, does it start faster?

If it cranks for that long, you most likely have a fuel issue as Bob noted. Cleanout the tank, fuel lines, carb bowl, main jet and see if that doesn't help. Make sure the choke is operating properly.

Didn't explain my situation very well. When you turn the key there is NO engine movement just a struggling noise/silence and then 10-15 seconds it fires up?

If I knew which motor you have besides a 18 horse , I might have a ideal on what to tell you.
Sounds like a bad ground going to engine

Briggs & Stratton 18.5 hp 7 years old... I know probably time to place at side of road!

Check your valve clearance /
Should be between .004-006
Top dead center then 1/4 inch past.
Luck