Whats spring loaded knob on jinma I pump

It’s the priming pump.

Yep it’s the priming pump if your tractor is running fine don’t mess with it.Only use it if you are changing filters or run out of fuel.

chuckinnc wrote:

OK, just never seen a priming pump like this. It is screwed all the way down with spring compressed, it takes about 10-15 turns ccw and then the plug and spring comes out in your hand as it unthreads it moves up about a inch and spring uncompresses before the spring and plug/knob pops out, you can’t pump it like a normal priming lever

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It should not come out in your hand! If it does, it’s broken. It should unscrew until it pops up, and when it does you push it back down without turning it, and begin pumping it up and down. When you are finished priming, push the knob back down and turn it clockwise to lock it. The CAV lift pumps have a lever. Not all diesel engines use a CAV lift pump. The type of lift pump you have is more common and is integral with the fuel injection pump, just like all Bosch pumps.

These pumps are available on eBay for cheap just look up Bosch priming pumps.I had to replace one on my komatsu d-21 loader it just threaded in to the pump.

My Mitsubishi mini-ex doesn’t even have one. It came from the factory with an electric fuel pump. Works great.

yep I have a JM454  Jinma whenever I change fuel filter or clean in line filter I just unscrew it till it pops up then pump it till you can feel it pusning fuel and screw it back in.