The float does two things, low fuel shut off and aux pump on/off
There has been talk of fuel pushing through the aux pump when using a large bulk tank
I added a fuel solinoid inline with the aux pump on mine just to be sure
I believe the float can be activated through the fuel filler by pulling the screen out
Unplug your main fuel pump when testing, maked it easier to hear the aux pump
Also check out Steel Solders, there are many discussions about the MEP 8xx series generators
