OEM Kohler #278490 12V Fuel Pump
Don't confuse this with the cheap knock-off pumps you see online for much less money, they are not the same. They are guaranteed to fail within 30 days. I've been a tech in the industry and a Kohler dealer for 45 years and trust me, I've tried using them myself only to have the same issue shortly after. You get what you pay for.
This is the OEM replacement plug in pump, no adapters or wiring modifications necessary.