Kohler gens set, switching to independent fuel tank and gravity feed

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Active member
Apr 25, 2018
So ive got a Kohler k321 engine on my 4kw gen set.  Normally it runs from the rigs gas tank but i have hard time keeping the tank full enough to allow gas to be picked up by the gen set line.  So I fabricated a small independent gas tank to run the generator.  Ive been toying with the idea of changing it from a mechanical fuel pump thats cam driven to just running a gravity fed fuel system and eliminating the fuel pump completely.  Normal gravity appears to be enough fuel volume to fill the bowl up as needed.  Has anyone done something similar and had any problems changing this setup?  Ive seen other kohler k321 engines on tractors and such that are gravity fed thats where i got the idea so im thinking theres no reason this shouldn't work on mine.  Any pointers or if theres something i haven't considered id be grateful.  thank you


Well-known member
Apr 16, 2014
Gary RV_Wizard said:
Why not a small electric fuel pump? 

If one uses an electric pump on the K321, they will also need a fuel pressure regulator. Many in the garden tractor world have tried the low pressure fuel pumps, and they still blow the inlet needle off the seat and cause flooding.


Well-known member
Jul 26, 2015
If the issue is simply, as you describe, having a hard time keeping enough fuel in the RV tank, I'm not sure how switching to a little tank that has to be filled much more often will make it any less of a problem. Don't you have to pour gas in a tank either way?  ???


One issue with gravity feed fuel is when the engine is off and needle seat fails, you fill the engine with fuel.

Lou Schneider

Site Team
Mar 14, 2005
Your problem with drawing gas from the main tank may be a leak in the short section of rubber hose between the tank and the metal fuel line running up to the generator.  The generator's fuel pump sucks fuel out of the top of the tank like drinking through a straw so if there is a leak, the fuel will fall back into the tank instead of leaking out.  If there are pinholes or a crack in the fuel hose the pump will suck air instead of fuel, especially as the level in the tank falls and it has to suck harder to get the fuel out.

The bottom of the fuel siphon tube is a bit off of the bottom of the tank so the generator can't drain the tank dry and leave you stranded.  But if the generator is starving out when there's more than a 1/4 tank of fuel, the culprit is probably a leaking fuel hose.
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