[w2much]

Well of course its probably a fuel restriction. My question is where does it sense the restriction from and how does it operate. I am certain my tank needs to be cleaned but how does this thing sense a restriction. Thanks.

[Faztbullet]

VRO(fuel/oilpump) creates a suction on the inlet side, if suction(vaccum) is to high, switch closes(shorts) to ground triggering horn