Float Bowl Vent - 1.9DG Pierburg - advice please

[StuM]

Hi All,

Carbs are not one of my specialist areas - in fact, I am blissfully ignorant in this area.

I found a fuel leak in the engine bay of my 1985 1.9DG van today, the hose that exits the carb to return to the tank - likely a split in the hose. I've ordered new hoses and clips to sort that out, but one thing that I don't understand is the operation of the fuel return to the tank - what I understand to be the float bowl vent.

The name itself suggests to me that there should only be vapour exiting into it, but it was a steady drip that was coming from the leak on mine when it was running. Does this suggest that the float valve isn't operating correctly?

Thanks,
Stu

[MidLifeCrisis]

Nope - that's working as it should;

The fuel pump delivers fuel to the carb where it collects in the fuel chamber; As the fuel level rises it lifts the float; When the float gets to a certain height it triggers the float valve; The valve prevents any more fuel entering the fuel chamber and instead diverts the fuel to the fuel return pipe (thus preventing a pressure build up).

So what you are seeing is the excess fuel returning to the tank.

The fuel vent thing is a separate feature that, as you suggests, just vents the fuel chamber (allowing air in/out and fuel vapour out as required) otherwise the fuel chamber would be sealed.

[StuM]

Brilliant, thanks very much for the explanation.