Buddy, check the links, some good info on diagnosing and fixes to your RTV's problem.
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Kubota RTV 1100 won re start after shut down
Rtv1100 OrangeTractorTalks Everything Kubota
How to Bleed Kubota Fuel Injector Lines

Unlikely to be injector seal washers. To allow such an escape of compression that it prevents starting would produce such a great noise it would be immediately obvious.

If the engine is a direct injection design in good condition, they typically start with minimal help from a cold start device though often necessary below freezing point.

An indirect injection design absolutely depends on an efficient cold starting aid even in relatively warm ambient temperatures.

I suggest cranking the engine with each injector pipe loosened at the injector in turn until air-free fuel is being delivered and then retightened. Once you are satisfied the system is fully air-free, with further cranking the engine should start - if the cold start system is functioning correctly.

Carefully using an ether spray might be useful on a direct injection engine but should never be used with an indirect injection engine when supplying copious amounts of hot air directly into the air intake produces the best results when the cold starting aid is suspected faulty.

Can't say much more without further details other than a minor air leak will allow fuel drain-back and prevent starting.

You are in the wrong category for this equipment. Please repost.