I think that your understanding of the specifications is correct. And the installation as described does not meet
those specifications.
Follow your own conscience. For a bathroom ejector, the pump will be moving only a few gallons per cycle. The toilet uses less than 2 gallons per flush, for example. And shower heads are now low flow.
Imagine that the specifications were possibly written to accommodate a laundromat with multiple washers-- possible huge sustained pumping load.
My opinion is that the installation you have will work fine for your application.
My opinion is that if you mention it to an inspector, all will have to be changed to comply with the code and/or manufacturer's specifications, whichever are the most stringent.
So that is the picture as I see it. Being very quiet keeps your options open-- blabbing eliminates most of your options.

I disagree with bus_driver.

First, Having an sewer ejector pit 'roughed in' for 'future use' without an actual sewer ejector being specified and installed at that time could have and should have been approved by the plumbing inspectors if it met code in 2004 and if the rough plumbing was done according to the approved construction plans.

Second, there are two different types of sewer ejectors:
A) Mechanical Ejectors and B) Pneumatic Ejectors.

The 1st type, mechanical sewer ejectors, usually only require a 1 1/2" vent pipe, and this vent can be connected to the plumbing vent system for the building without going directly through the roof.

The second type, pneumatic sewer ejectors, usually require 2" vents that must be vented directly to outside air.

That said, whatever type sewer ejector you are now trying to install must be installed to current codes and to the manufacturer's installation instructions.

Seems to me your current ejector is not compatible with the existing vent system, so you have two options:

1) Install an ejector (mechanical type) that is compatible or
2) Install the venting required for your apparently current (and possibly pneumatic) type.

PS:

You probably need permits to install whatever ejector system you wish to install, so contact your local code office for details and guidance.

Have not looked recently, but the IPC specifes 2" and 2" without regard to the pump type or capacity-- if memory serves correctly. Your code may be different. Most codes also require that any included manufacturers instructions must be followed as those were considered in any certifications such as UL CSA, ASTM, etc.
So factor that into what I posted earlier.

Agree,

And for the record I was not trying to poke you in the eye with my comments, bus_driver.

Maryland uses the Uniform Plumbing Code if I remember correctly.

I am under the International Plumbing Code.

Whether local plumbing code or the manufacturer's installation instructions apply normally depends upon which requirement is the more 'strict'.

That said, there is usually a difference in venting between mechanical and pneumatic type ejectors, with pneumatic ejectors needing to have direct venting since they, unlike mechanical types, discharge under pressure.

Bottom line is:

Contact your local plumbing code office for real guidance.

My opinion continues to be that the rough in plumbing was correct and should have been approved at the time of installation.

The original poster either needs to install a sewer ejector that can use the existing vent system or install a new vent system compatible with the type ejector he chose to install.

To understand my perspective, I lived part of my childhood without electricity or plumbing. We were so glad when we scraped up enough money to get those. Only electrical inspections were required and the inspector did those seated on the swing on his front porch. Fast forward-- three times in my experience as an electrician (one of my careers), an unknowing inspector has held up my job because of his ignorance-- causing my customer to doubt me and my ability- and causing me several lost hours and many extra miles of driving. In the end, my work was passed as it was done originally. In two of the cases the delay was 8 days. Found two inspectors in the same department who interpreted the same code section exactly opposite from each other - one of them was correct. And that is just a few of the instances.
So I am now gunshy and avoid inspectors as much as possible. But I do the best installations of which I am capable.
In the early days we had two plumbers in our area-- one was an alcoholic and did such things as supplying commodes from the hot water line. The other one had an unlisted phone number. We just did most of our own out of necessity.

Thanks for all of the input.

I was unfortunately looking at the wrong documentation online. I have the Zoeller 267 pump. It makes no mention of venting requirements, just that it have one when installed in sewage situations. It even states it can have a 1-1/2" output.

So it looks like this pump is compatible.

I'll double check with another licensed plumber just to confirm.

Thanks again!