Are you absolutely sure this is the correct schematic for this specific tractor?
Sometimes a Model number even 1 different can have a very different schematic or just a minor deviation.
Would you post the Sears 917.xxxxxx number just to verify please.

Are both engine kill conditions occurring when in the seat?
Are you engaging the PTO with the clutch depressed and the engine still dies?

The model number is 917.250510. And I couldnt find a schematic using this model number. This schematic seemed to be the best match for the tractor. There is only one seat relay. Sitting in the seat the relay does work. Sitting in the seat let out the clutch to drive and it kills the motor. Push the clutch in and engage the pto and it kills the motor.

Totally different schematic-
The one you posted shows power through the seat switch AND an Operator Presence Relay.

Click the link for the OM
Page 30/64

Your symptom indicate a bad or mis-adjusted seat switch or seat switch connector unplugged.

Here is a link that might be useful: Owners Manual

Something is amiss.
I went to the Sears Direct website and downloaded the owner's manual for 917.250510. The manual shows a schematic.
The schematic for 917.250510 DOES NOT show an Operator Presence Sensor relay.
You state that you have checked "the relay" so I infer that you can confirm there is a relay on the tractor?
Be more specific when trying to relate to us where you are "touching" with the meter leads. Saying the "two outputs" of the relay are not grounded together does not really make it clear which two terminal you are testing. The terminals are numbered and those numbers are what you should state when describing where you are testing.
I have to think you are referring to terminals 86 & 30 as being the outputs. Now I may have misunderstood what you are trying to get across when you stated that "86 & 30" are not connected together. If you mean that the relay is not shorted, and therefore not defective......you are correct insofar as 86 & 30 are concerned. But IF you think that 86 & 30 "should be" connected together when you test, read on.
If you are testing for continuity between terminals 86 & 30 with the relay unplugged from the wiring connector........you WILL NOT have continuity........because the "connection" shown on the schematic for 86 & 30 is not internal to the relay......the connection is accomplished by the wiring harness.
86 & 30 only become connected to a common ground circuit when the relay is plugged to the harness connector.
Recheck the model number to see if you have something wrong in those numerals.
And if you checked 86 & 30 with the relay unplugged, plug it back up and retest by probing on the backside of the connector where the wires enter the connector.
Have you tried unplugging the relay to see what effect that has on whether the engine stays running?
The relay is a common Bosch 5 pin relay that can be found just about anywhere (auto parts, small engine shop, etc.).
And they are cheap enough to swap out for testing purposes.

Ok, Didnt think the previous owner changed the wiring as well but it looks like that is a good possibility. The tractor originally had the 19hp opposed cylinder engine but it went bad before I bought it and it has a later model kohler vwin style motor. By output of the relay I mean 87 and 87a. When the seat is occupied the relay clicks and 87 is grounded and not 87a. With noone in the seat 87a is grounded and not 87. I didnt try to drive it without the relay in place. I discovered it would drive if the electric pto clutch was disconnected by accident.

It's just too illogical to make such unneeded wholesale wiring changes to simply swap an engine.
Why would one change the key switch, seat switch and add a relay when there is absolutely no need to?

Somethings fishy.

87 & 87A can actually be considered "inputs" as this relay is configured into the wiring scheme.
87 is input from the PTO clutch which seeks a ground to run the PTO clutch operating coil. If the relay and seat switch are good, the relay will operate when the seat is occupied and 87 will be connected to terminal 30 (output to ground here) and the PTO clutch will engaged when the PTO switch is switch to ON.
87A is input from the magneto kill circuit and if the seat is not occupied, the relay remains inactive and 87A will stay connected to 30, which will kill the magneto and stop the engine.
Put a new relay in place and then see whatcha got.

The other tractor that is identical engine and wiring is 917.251551 and the tractor ran fine for the last 5 years I havr had it. I will try a new relay this weekend when I go back over to the inlaws. I should have several of the bosch type relays in the garage.

Thanks
Mark

I don't understand why you posted a schematic that doesn't match either a-
917.250510 Kohler MV20S-57529
OR
917.251551 Kohler CV22S-67515

Hardly "identical" engines!

Why shouldn't we believe you aren't simply screwing with us?

This post was edited by bill_kapaun on Wed, Sep 11, 13 at 10:02

The other tractor that is identical engine and wiring is 917.251551 and the tractor ran fine for the last 5 years I havr had it. I will try a new relay this weekend when I go back over to the inlaws. I should have several of the bosch type relays in the garage.

Thanks
Mark

Bill your not following what I am saying. The 917.250510 has at some time before I bought it had a motor swap and now has the same engine and wireing as my other gt6000 model 917.251551 .

Sorry, I thought they were wired the same but on closer inspection on the 917.251551 I have at my house it is the same motor but slightly different wireing. This one doesnt have the operator presence relay and a different ignition switch. The scematic at the origional post is the closest schematic I could find to what I was working on.

Since neither had an OPR, how did they magically grow one?

Are you sure you're getting the correct model #'s?
You can go to-
searspartsdirect.com
and download the manuals for both and see for yourself.

Just had the mother inlaw go back out and confirm the model number under the seat is 917.250510 . All I can think is for some unknown reason the wireing harness was swapped out when the motor was swapped. It definitely has the operator presence relay since it has a 12v feed from the seat to the relay coil.

Well, let's go by the schematic you posted.

Anything that grounds the "M" terminal of the key switch grounds the kill wire and thus, no spark.

With the key in the ON position (thus M isn't grounded at the key switch)-
Hook your OHM Meter to the kill wire-
disconnect the various gadgets that may ground the kill wire.
OPR
Clutch/brake switch
PTO switch.

See if you can eliminate or isolate the problem that way.
You might have to try different combinations??

Maybe, if it was "re-wired", they have the key switch wired incorrectly. Your schematic shows a 7 terminal switch vs 5 terminal originally installed.

Your schematic has the top & bottom cut off, showing the model# (top) and "truth table" (what each switch position does) on the bottom.

IF this has the original seat switch, that WOULD be a problem.
That switch is NC, while the one in your schematic has to be NO.

I did test the seat switch with an ohm meter and it is a normally open switch and is working properly. Will try to isolate more Saturday when I go to the inlaws.