Walbro LMK Carburetors???

[38racing]

Anyone know of a reasonably priced (around $25 or less) reliable 12v inline type fuel shutoff solenoid that could be used on gravity fed lawn tractor engines. (to reduce possibility of crankcase flooding))

I know of one but the current draw will tax the stator; unless, you are using the 15 amp stator. It draws nearly 3 amps. The vacuum operated one I seen on a Chinese ATV makes more sense.

Vacuum operated?

Wonder if one of these vacuum operated type fuel pumps would also be Ok as a fuel shutoff solenoid to stop fuel flow from a gravity operated system lawn tractors that use the Walbro LMK type carb or similar carbs.. (would the diaphragms inside the vacuum pump hold back fuel flow from a gravity system when engine is not running)
Reason I ask is it's less than $10 vs cost of a electric solenoid valve. I've used these type pumps when the gas tank is lower than the engine but do not know if they could be used as a gas shutoff from a gravity system when engine is not running and I do not have any vacuum pumps in stock right now for testing?

https://www.ebay.com/itm/Gas-Vacuum-Fue ... SwU1FXP7HA

A friend gave me a rider with briggs OHV twin on it. Big tank so gravity would work until it got real low but it has vacuum pump. I got it because it flooded and he couldn't be bothered with cleaning the gummy carb. I assumed it flooded while sitting, not while running. Hasn't flooded on me but I installed a shutoff valve.

[KE4AVB]

Vacuum operated fuel shut off valve (solenoid) and vacuum fuel pump are two different animals. Also you can't use a fuel pump on gravity systems as it will over power the carburetor float needle valve.

[38racing]

Vacuum operated fuel shut off valve (solenoid) and vacuum fuel pump are two different animals. Also you can't use a fuel pump on gravity systems as it will over power the carburetor float needle valve.

like this I assume.
https://www.amazon.com/UMPARTS-Vacuum-V ... B06Y53S899

[KE4AVB]

Yes that would what I was referring to. They use the same principle as the vacuum operated fuel pump except automates the the manual fuel shut off valve as kids don't listen very well and those kid's ATV carbs are some of the cheapest designs.

Now if the fuel bowl is empty it will take a little longer to start as it got to refill.

BTW they had 9 now they have 4. I wonder why. It couldn't be someone like me ordered them as they have been looking for them for a while. Tnx for the link.

[Arkie]

Vacuum operated fuel shut off valve (solenoid) and vacuum fuel pump are two different animals. Also you can't use a fuel pump on gravity systems as it will over power the carburetor float needle valve.

I tested a Briggs vacuum operated fuel pump and gravity fuel still flows through with no vacuum applied. (cannot be used as a petcock valve).

[Arkie]

Vacuum operated fuel shut off valve (solenoid) and vacuum fuel pump are two different animals. Also you can't use a fuel pump on gravity systems as it will over power the carburetor float needle valve.

like this I assume.
https://www.amazon.com/UMPARTS-Vacuum-V ... B06Y53S899

Thanks for the link.

[KE4AVB]

I tested a Briggs vacuum operated fuel pump and gravity fuel still flows through with no vacuum applied. (cannot be used as a petcock valve).

That is because the fuel has two one way check valves. As vacuum is applied the inlet check valve opens allowing fuel while the out flows closes. Once the vacuum is released and since is not metered it immediately starts pushing on the fuel closing the input check valve and opening the outflow check valve. Now when the pump is at rest any pressure from the fuel supply will open both valves allowing fuel flow just as it there no gating; unless, you're trying to reverse flow the pump which that case one or both check valves will close preventing fuel flow.

If you ever paid attention the fuel pump diaphragm inside a Walbro or Zama cube carburetor they operate much the same way.