Facet Q

[Nacho]

Technical Q. Is this Facet PSI to much, will it damage anything, when installed on my 582 fuel system. I saw 1.5 - 4.0 PSI is enough.


Part Number 60106
Pump Posi-Flow
Voltage 12v
Pressure (Psi) 4.0-6.0
Flow:- US Gallons/Hr 32
Dry Prime
Height in Mtrs 0.3

[cjkrit]

I think the pump you need is the 40105 and it often comes in a kit with number 40242. It delivers 1.5 - 4.0 psi. If you go way down this technical talk section you will come across : "Installing a backup fuel pump". Think you will find answers to all your question there. Good luck.

[Morph]

yes that fuel pressure is too high

[Nacho]

Thank you Morph. Just 1 Q. In the Rotax manual they say the pressure of your mechanical pump must be between 0.2 and 0.5 Bar (Which is 3 - 7 PSI) Why then is a Max 7 PSI Facet fuel pump too much?

Sorry, must sound blond, but I dont understand. Surely nothing can get damaged if you use a electrical pump that matches the max PSI rating of the mechanical pump? What am I missing?

[Morph]

If you run them together, (which is what is going to happen if you run it on take off and landing) you can can put too much pressure on the carbs. The needle and seat is the only thing stopping the fuel from overfilling the carb. The needle and seat are kept closed purely by the float level. With too much pressure the fuel can push past this and start overflowing out of the breather pipes. This obviously is not a desireable situation especially if near an exhaust.

[Nacho]

After installing my new Facet pump yesterday Facet 40105 3 - 4.5 PSI, I have a small problem.

I have a Cobra with 2 x Pickups on the top of the tank. I installed a filter after the one pickup and the Facet just after that going to a T piece.
On the T Piece I have the second pickup connected and the 3rd part going to the main fuel filter, then to the mechanical pump supplying the two carbs.

I rebuilt my carbs, from scratch. So when I installed everything yesterday, and after running the Facet for about a minute. Pls Note: completely empty carbs. I could not get the 582 machine to start. The carbs stayed empty. Eventually I manually filled the bowls and tried again. I started in no time, and it ran perfectly.

2 Q's

- Wasn’t the Facet pump suppose to fill the carbs bowls?
- Did this happen due to air in the fuel system?
- Will this pump be sufficient, to supply the carbs when the mechanical pump fails? Seeing that it didn’t fill the bowls.

Please note. The Facet is installed at a higher level that the fuel level, due to the pickups, coming out on top of the tank. I will say about 10cm higher than the tank.

[Morph]

the facet is a one way pump. Fuel picked up by the facet is returning to the tank via the other pickup

either put in a one way valve on the other pickup, or preferably put the facet in series

[Morph]

2 Q's

- Wasn’t the Facet pump suppose to fill the carbs bowls?

Yes it will, you will hear the pump with a sharp sound and later as the pressure builds the sound will become dull)

The Facet is installed at a higher level that the fuel level, due to the pickups, coming out on top of the tank. I will say about 10cm higher than the tank.

the pump will work fine, it can suck fuel up to a meter higher than the tank and it is self priming, i.e. will suckout theair first.

[Nacho]

Thanks Morph. Will go the non return valve route. Was mission to mount the Facet, so I dont really want to move it now.

Your help is much appreciated. It actually makes a lot of sense, doing it like that.

[Morph]

You already have the facet in series, just disconnect the return line

[Nacho]

Ok, so you mean taking the second pickup out of the circuit completely? Blanking it off?

Taking the output from the Facet, directly into the mechanical pump? Why does it have 2 pickups in the 1st place?

[Morph]

very good question, there is usually only 1 pickup and the series setup works perfectly. The facet will allow the fuel through without obstruction

another way of doing it is a competely parallel system,

[Nacho]

Thanks Morph. Will go the series route and disconnect one fuel supply out of the fuel tank completely.

Tried getting non return valves. Not easy to find. Would also like to keep it as simple as possible.

[Morph]

are you sure that the second "pickup" is in fact one, i.e. has a tube extending down to the bottom of the tank, and not the airbreather pipe, that is a hole on the top of the tank allowing air in.

If it is an airbreather, perhaps it needs a tube extending upwards against the airframe to prevent fuel overflow.

[Nacho]

Two lines comes from the top of the tank. The one has a breather pipe next to it, going up and cable tied onto the fuel line. Both fuel lines goes from the tank, into a T piece. From there it is routed to the mechanical fuel pump, that goes to the carbs.

I connected a the Facet to one of the pickups, going to the one side of the T piece. So obviously this doesnt work as I pump fuel back into the tank, silly me

So what I will do now, is blank off the one pickup. Remove the T piece and only use the line on which I installed the Facet. Thus pumping fuel directly through the filter into the mechanical pump. I installed another filter at the pickup comes out of the tank, before it goes into the facet pump. So now I have two fuel filters in the line.

This should be ok? Most microlights just have one pickup, I wonder why the Cobra has 2.