you prolly first need to determine of you have an ignition problem or a fuel delivery problem.
Begin by removing the engine air cleaner. Have an assistant to spray several shots of rattlecan carb cleaner directly down the carb throat while you normally crank the engine to start from the operator's seat.
If the engine attempts to start (fires several times), you have a fuel delivery problem;which could be a fuel line restriction, a fuel pump problem, a fuel filter problem, a carb prob or an afterfire solenoid prob.Troubleshoot and repair as needed.
If engine does not attempt to start per above, then check ignition, including seat switch. Remove plug, hold threaded body to engine metal body, re-attach ignition wire lead, crank normally. Should observe a bright blue-white spark - not weak or yellowish.

I am not sure about your 2166, but most of the newer machines' seat switches have a built- in interlock prevention that effectively stops an user from simply disconnecting them to disable the function. If you do, Your engine will not start, as I understand it.

If your machine has been exposed to outside weather (rain, snow, etc.) or has had heavy doses of cleaning via pressure washers or garden hoses, you may now be experiencing random electrical probs caused by corrosion.

But, would first suspect faulty seat switch followed by carb probs based on your description so far. good luck

Seat switch was bypassed. The motor starts fine but will not stay running if I jump the solenoid. It has to be either a pto switch or a relay somewhere and not sure best way to narrow it down other then dishing out cash for parts I cant verify are bad. It is definitly not a mechanical engine problem it is electrical.

Thanks
Shad0wjack

"I am not sure about your 2166, but most of the newer machines' seat switches have a built- in interlock prevention that effectively stops an user from simply disconnecting them to disable the function. If you do, Your engine will not start, as I understand it."

I don't have a schematic for your tractor, but "bypassing" the switch seldom does the job.

Do you know if your switch is NO or NC?
Do you know the connector likely has a shorting tab integral to it?

Seat switch is NC.

Diagram for my Wiring

I can't make out the schematic. Just too blurry for these old eyes.

How did you "bypass" the seat switch?
Typically just disconnecting the plug guarantees a no start condition.

OP - waitaminnit... you start by say yer machine "will not start"... then you post back saying "The motor starts fine but will not stay running if I jump the solenoid"....

Have we got 2 separate threads going here? Bill, yer on yer own - I'm outta here.

Bill - I disconnected the 2 wires and connected them together.

rcbe - It will not start with the key, and I did say it starts by jumping the solenoid. It's an electrical not mechanical problem.

Bill - I disconnected the 2 wires and connected them together.

rcbe - It will not start with the key, and I did say it starts by jumping the solenoid. It's an electrical not mechanical problem.

OK, it's time once again to define the correct terminology for certain actions.
STARTING is what happens the moment the engine begins to run "all by itself" after having been CRANKED.
CRANKING is what takes place in order to spin the engine so it will (hopefully) get started and run on its own.
When the key is turned to the start position, and the starter motor activates to rotate the engine................that is known as CRANKING.
IF the engine is in good order, CRANKING will result in the engine achieving START status. After the engine has STARTED and CRANKING is no longer required to spin the engine, the engine is considered to be RUNNING.
So, having explained the definitions............do you have a CRANKING problem? Or, does the engine CRANK without STARTING?

"Bill - I disconnected the 2 wires and connected them together. "

IF by disconnecting, you just pulled the plug, you'll likely have a no start.
Connecting them together will likely result in no start also.

Most the seat switch plugs have a "shorting tab" as part of the plug.
When you remove the plug, the tab slides in place and results in a connection, which grounds the kill wire.
Connecting the wires together also grounds the kill wire.
Either scenario KILLS the spark. That's why it's called the kill wire.

As Mownie asked-

Is it a cranking issue or a starting issue?

He aint gonna answer imho - he used pa-pa over on eMTeeF to get what he needed and was gone in a flash. real class.

i have an old Cub Cadet 2166, and it started acting up so i began to trouble shoot the maching, this time, i found the switch plug was partly out and push it back in and the unit ran fine

I would like to know about a replacement oil filter and oil for my 2166, cub cadet transmission

wpnoble - s/b able to look in the cavity under the tilting seat, get the full model number and serial number off the ID plate: do a Google search for "MTD manual archives", enter the requested info, d/l a manual (parts or operator's) for your machine, find the correct replacement part numbers and replacement procedures.

Your machine is a 2000 series, so a good chance that the tranny may be designed for oil and filter maintenance. If not (sealed for life type), then will require removal from tractor , turning upside down, a slow full drain and refill.

My 2166 owner's manual specifies a Cub (MTD) part# 923-3014 for the transmission. Specifications are the same as a Fram PH2844 (this is what I use), or NAPA 1410, or Motocraft FL-268

They used a couple different transmissions on the 2166's. I think the filter is the same, but like RCBE suggested, having your serial number is key. You can also do a simple web-search for Cub Cadet 2166 and find several online retailers who have full parts lists and diagrams for these machines.

wpnoble - one caution - be careful if optioning for an aftermarket filter - their internals may not match up, effectively disabling your tranny. Best to stay with the specified OEM in this case, IMHO...

Ditto to what RCBE posted.

Hydraulic filters are not the same design as oil filters. Best to go with the actual OEM filter.

The FRAM & NAPA (or WIX 51410) filters mentioned above are good matches.
The Motorcraft has different gasket dimensions and isn't specified for hydraulic.

Kapaun - do you confirm that their internal bypass characteristics are the same as OEM?

The OEM part number is 923-3014 and SRP is $14.50

Why take a chance as rarely as trans filters are changed?