Craftman Riding Mower Model 917. 289250 Power loss and shut down

So I have had this mower in operation for about (385 hrs) it’s a Craftsman Model 917. 289250 (27 hp) V- twin; orginally (24 hp) but it was returned and they swapped (Sears) engines for some reason and placed that 27 hp motor on instead. Not sure the reason. I have recently been having issues with the mower. I noticed that the speed of the mower has gone down dramatically, enough were you notice something is not quite right. The second issue is that after about 40 min of operation sometimes less, it starts to lose power and will eventually, just run down and shut off. I’m not sure if it is a fuel delivery issue or carb issue. Maybe you guys are more familiar with this issue. I have kept regualr maintaince tune-ups and such. If i let the mower sit for about an hour it sometimes will start right back up. Sometimes it won’t.

It will be shutting down either because of a dud coil or a fuel blockage.
So grab a can of carb cleaner and an red flashing in line spark tester ( 2 would be better ).
Fit it (them ) to the engine & go mow
When it stops crank the engine and check that both of the testers are flashing.
If they are then spray a very short shot of carb cleaner down the carb & crank again.
No flashes = electrical problem
Runs on carb cleaner = fuel problem


As for the loss of power
check both testers are flashing at the same speed.
If one flashes more than the other = electrical problem
You say you have done regular maintenance on the engine, did that include checking the valve lash ?

Thanks for the advice bertsmobile1

Ok, I will try both of the tips you have provided me with. I have not checked the valve lash before not even really sure what that is but, I will research this. My regular maintenance consisted of basic change spark plugs, Oil changes, fuel filter, fuel line and air filter.

It is the space between the rocker & the end of the valve to allow for expansion & spring lag.
You remove the rocker covers and check them when the piston is at its closest to the spark plug and the inlet valve ( top, one ) has closed.