Fuel filter/water separator draining

[Guest]

I have a Delphi pre filter fitted to my boat before the fuel lift pump. It has a metal bowl with a drain.

If I open the key on the bottom to drain off any water will I have to bleed the fuel system?

[Antares_9]

Probably not, it really depends on how much you have to drain. If you turn off the fuel tap whist doing it that will help, otherwise as you crack the drain fuel can run back into the tank and empty the line, then you will need to bleed. Don’t be feard if you do have to bleed though, it’s hardly a major job, yet, best if you can avoid it.

[Guest]

Great, thank you.

[Hockham Admiral]

Probably not, it really depends on how much you have to drain. If you turn off the fuel tap whist doing it that will help, otherwise as you crack the drain fuel can run back into the tank and empty the line, then you will need to bleed. Don’t be feard if you do have to bleed though, it’s hardly a major job, yet, best if you can avoid it.

I can't see why, David, as surely the weight of fuel (if your tank is nearly full) will push fuel down the line into the filter/water-separator? (just to drain a few cl's of water off)

[Antares_9]

Depends if the filter is above tank level as it should be John, if so then as soon as you allow air to enter by opening the drain valve then the fuel like any fluid will find its own level by draining back as far as the level in the tank. Easier just to switch off the tap and not have the worry.

[Hockham Admiral]

Of course, David. I checked ours again this morning and they are actually water traps and as such are below the tank level. They then go on to the diesel heater and the engines, all of which have their own filters.