L3250 Loss of power after tractor warms up

[J03bota]

Hi guys,
I have noticed that my tractor started losing power after it warms up. It recently has gotten pretty bad?
I just changed out the fuel cap and fuel transfer pump. Glad I did it (since they were the original parts) but it didn't solve the issue.
Also, fuel tank and fuel filter are clean.

I plan on checking the valve gaps next week. Its been a few years since I checked the valve gaps. I do remember that I set the gaps a bit tight so if anything I would think the power would improve over time.

Besides a valve gap issue what else do you think it could be???
Before its fully warmed up I can climb my hill in 6th gear with ease.
After fully warmed up the tractor stalls at about 3/4 the way up the hill.

Thank you.

 

[Roadworthy]

Start by making sure you have good fuel flow from the tank. You may have algae clogging the outlet allowing fuel to slowly fill the lines but not at a fast enough rate to sustain power. It's also possible you have a fuel filter issue or if there's a water collector it may need drained. Be careful setting your valves. If not enough clearance is allowed it is possible to have valves not close completely when engine warms up.

 

[J03bota]

Hi, thank you. If the gaps look good, I will drain and clean out the tank and install a new filter. I always use fresh fuel and always use the recommended additives but you never know. Since I have owned the tractor (~10 years) I have never cleaned out the tank. So its definitely worth doing either way.

 

[J03bota]

I checked the valve gaps and discovered that both cylinder 3 valve gaps were too tight. I adjusted them to spec and the tractor performance is back to normal.
Seems strange how both valves on cylinder 3 had some wear? The other valves never moved?
Hmmm. Maybe engine lube doesn't get to these valves as quickly?
Any thoughts are appreciated.