Ok, I am stumped. I have a Z 915 B that I purchased new a few years ago. This past weekend, I fired up the mower for the first use of the season and mowed for about 4 hours without issue. When I was done for the day, I washed the mower with a garden hose and then put it back in my garage. The next day I went to use the mower and noticed that the engine would not run at full speed. After messing with the throttle for a bit, the motor finally ran at full speed like it was supposed to and I proceeded to mow again for about an hour. Later that day, I went to put the mower away and noticed that the motor would start and idle without issue, but would only get to about half to 3/4 speed.
It starts fine, idles great, but when you give it full throttle, it only revs to about half to 3/4 speed. If the deck is running, the blade speed is way down and the mower will stall if you try to cut any grass.
If the deck is not running and you drive around, the motor will almost stall out if you give it full forward input. Forget about trying to go up any hills.
If the mower is running and the throttle is set to wide open, I can manipulate the linkage and get the engine to rev like it should, however the governor will throttle it back.
The throttle cable has plenty of range, so that does not appear to be the problem.
I checked and cleaned the air filters, put a new fuel filter on it, and I also cleaned the spark plugs, but the engine will not run at full speed. I am kind of stumped on this one so I was wondering if there was anything else I should check?