Lazer Z surging engine problem

So we just got our first Lazer Z mower this past week! Very excited about it! All we know is that it was used on a gold course and has 2550 hours on it, I think it is a 2012, it is a S series with 72" deck. We changed out the oil and oil filter and the hydrolic fluids and added a gallon of new fuel to it, so now it is full, the gas in there before may have been a little old, not real sure. We also changed the spark plug. We noticed that after we got it home and started it up, BEFORE changing the fluids.. that is seemed to surge up and down in the mid to mid-upper range on the engine speed while you are sitting there. Once you get going and you push the engine speed into the upper range it seems to smooth out. The lower range seems ok too.. just that mid range. Just wondering why it might be doing that.. still does it after we changed the fluids and filter, and spark plug and added fresh fuel to it. Could it be the fuel regulator? The visible inline filter looks clean, not sure if there is any other fuel filter..What do you think?:confused2:
Thanks!
Jen

:welcome:
The fuel filter is somewhere between 25 and 75 microns.
You can not see that small.
Water can also block the fuel filter & you won't notice it.

Most likely it will be the main jet in the carb partially obstructed.
Pull the carb right off, clean it out then reassemble with new gaskets & needles.

This is an EFI model 747 Comander, Kohler engine so no carb.....?

bertsmobile1 said:

:welcome:
The fuel filter is somewhere between 25 and 75 microns.
You can not see that small.
Water can also block the fuel filter & you won't notice it.

Most likely it will be the main jet in the carb partially obstructed.
Pull the carb right off, clean it out then reassemble with new gaskets & needles.

Click to expand...

omni said:

This is an EFI model 747 Comander, Kohler engine so no carb.....?

Click to expand...

Which is exactly why we beg and pleed for posters to start by telling us what the engine make model and code numbers are and what the mower model number is.
But for most it is like extracting teeth to get the basic information needed.
You are there we are on the other end of the wire and have no idea what you have unless you tell us.