Old & Slow wrote:
Ok, I get it. Need to turn the petcock off after using the genset. But, could you give us more info' and link to a 'electric fuel transfer pump' And how would that effect the gravity feed/needle seat? Safety is a wonderful thing.
Electric
transfer pumps
may be fine for moving gasoline from one tank to another provided that you are using an actual explosion proof electric fuel pump and not some jury rigged device, are absolutely positive no source of static electricity arc or battery connection spark is nearby (including ignition sources from RV) and, of course, a fail safe overfill protection device is installed. Additionally, good ventilation is always required - especially when working with closed spaces. If you are not familiar with this concept do a little reading related to the requirements for fuel and the venting of installed fuel tanks as per marine applications with pleasure boating. This is the reason I have treated the "cave" as one should treat a bilge on a boat.
I guess you have all ready assumed all of the above can easily make an electric transfer pump cost prohibitive. The vacuum transfer method discussed earlier is much less expensive and safer.
Now to the float needle:
A small amount of gasoline that remains in a carburetor float bowl acts as a flotation fluid for a brass, cork or plastic circular float that pushes a small needle valve against a seat (seal) to prohibit fuel from a fuel tank flowing into the carburetor.
Just as when an adult tries to use a child's small swimming pool flotation tube as a water support device only to discover he sinks while the kid floats, the carburetor fuel bowl float is only capable of a specific amount of buoyancy in relation to the amount of liquid it is displacing and the weight (gravity or counter pressure) that is being applied to the flotation device.
The counter pressure on the carburetor float will increase as the total weight of the fuel above the needle valve increases within a predetermined volumetric area. In the case of the Chinese generator fuel tanks, their design is a large, relatively flat tank that has maximum area and minimum height. Still, as fuel is added and the fuel becomes โstackedโ overhead the weight of the fuel will cause an increase in pressure on the float bowl needle.
If too much fuel is โstackedโ the weight of the fuel may overcome the counter pressure that is being exerted by the float in the carburetor fuel bowl pushing up on the needle and seat and fuel will enter the carburetor, overflow the container and find somewhere else to go as long as the pressure above exceeds the pressure below.
It is interesting to note that on the smaller inverter style gensets (Honda 1000i, 2000i, Kipor, etc.) the RUN โ STOP switch on the engine also includes the fuel shut off. When you shut down the engine, you automatically turn off the fuel. If the fuel valve is turned on and left on with the engine not running and the fuel should leak past the needle valve, there are specific drain tubes to route fuel to the bottom of the generator case. This prevents fuel from running back into the engine and contaminating the crankcase but does nothing for raw fuel being spilled into an enclosed compartment where the portable genny may be stored. This type of genset also has a fuel cap that can be put into an unvented position. Great to stop leaking in transit but a real problem as temperature changes and fuel expands โ thus increasing pressure up to 15 psi in a closed tank.
None of the GX200 style carburetors I have encountered on the Chinese gensets are specifically designed to withstand pressures on the float needle exceeding 2-3 psi. Their typical operating pressure is design rated at around .5 psi.
In summary โ be careful and turn off the fuel petcock when the engine is not running! Not with just these generators but with your pressure washers, lawn mowers, garden tillers, pumps, or any other small gasoline engine with the fuel tank higher than the carburetor float bowl.
IMHO, forget about electric transfer pump systems as well. Too expensive to do it right โ thus too many shortcuts are taken creating greater risks. The safest method is in reality filling the genny tank from an approved transfer
container like a red โgasoline onlyโ flex spout plastic fuel jug.
Professor Randy T. Agee & Nancy Agee. Also Oscar, the totally ruined Dachshund.
2009 Cedar Creek 5th Wheel - 2004 Volvo VNL670 class 8 MotorHome conversion as toter.
Turbocharged, 12L, 465 HP and 1,800 ft. Lbs. of torque.
