Kubota L4400 HST Has no power in high gear

[moship]

I'd consider the use of some algaecide in the fuel if the filter was slimy. Almost sounds like the tractor had set for some time without use.

The fuel may or may not contribute significantly to the high range issue, but the advice above is spot on. Contaminated fuel can become a big issue and suggest it is corrected for future trouble free operation. If the fuel has slime (bacteria growth), I prefer to drain the contents. Fill with fresh fuel, add your treatment of choice at shock level (ratio) followed by maintenance ratios there after.

Many times the fuel can be drained by disconnecting the rubber fuel line before the filter. Draining in a light colored (white) bucket will make it easier to see the condition of the fuel.

Here's just one example of a biocide additive: Bio Kleen Diesel Fuel Biocide - Power Service

Best to keep fuel topped off to minimize condensation buildup over time.