Gull 2000 Fuel System : newbie

[ukey4917]

Hi, See attachment (pdf). I am a new guy to the group. Anyway I have Dick Walker's Gull 2000 5119D.It has a Rotax 503 Dual Carbs. There is this red handled valve on a fuel line that is downstream of the visible (transparent cylinder) fuel filter (located on the line from the bottom of the 10 gal gas tank (this one has the oil injection system) but before the Facet elec pump. This mystery line has a sintered filter and a closure valve (red handle) in it and it enters the top of the gas tank. I am attaching a diagram that I made by hand. I am wondering what this is and how it operates and what I should know about it for my flight operations. Thanks. Tommy (aka Gary on this list)

[blaswichk]

Might be that the red valve allows the tank to be removed
without fully draining.

[earthstaraircraft]

Remove all fuel shut off valves from the system. This system can not benefit from a shut off. But sometimes people forget to turn them on and have an engine failure
on take off.
Happy Flying
Mark Beierle
Earthstar Aircraft
Sent from my iPhone

[ukey4917]

Hi Mark and Kess et al,Thanks for the input. And especially to Mark as I now understand that NO c/o valve is the best b/c one day (being human) I will forget to set the valve to open. That will take a bit of work on the Gull 2K that I have to make it happen. Now back to the interim question as to what the heck is this thing? Attached find two photos (now downsized to conserve bandwidth) that show the mystery red handle valve. Any comments appreciated.Tommy (aka Gary)

[billbango]

If that line goes to the bottom of the tank it looks like an alternate fuel source in case the filter is plugged.

[ukey4917]

Thanks for the reply. One day soon I will use an endoscopic camera and look inside the gas tank to see where that tube goes.That is good supposition as to possible fuel filter clogging. The main filter is one of those multi-part (about 1" in diameter and 3" long with a clear barrel): I now understand that they are not preferred due to multipart construction. For now, my test pilot has turned the red handle valve to OFF because the supposition is that the "top" tube could introduce air into the system. Today I watched a video that showed that serial pumps (electric in line with vacuum) is a bad idea in that failure of the diaphragm in the vacuum pump will allow raw gasoline to enter the crankcase via the pulse line. Further, the video suggested use of parallel systems (electric and vacuum) each plumbed to supply fuel to each Bing Carb. Based on what Mark said earlier (no valves in fuel systems) I can visualize a sintered filter in each of two separate lines coming from the gas tank with the lines going to each carb. This would require a Y upstream of each carb and likely a check valve (to prevent reverse flow). Now we have the conundrum: introduction of a set of one way (check) valves in a fuel system. Any ideas?

[cossitt.alan]

Don't see the need for the check-valve (am I missing something). don't have
one in my system, which is set up per Mark's specs. The electric pumps have
one already.

[earthstaraircraft]

Remember to keep it simple.
Some people don't have experience with vacuum fuel pumps and worry about diagram failures but I have never herd of that happening.
Fuel pumps have check valves.
The red valve on top of your tank will shut off your fuel. Before you fly run your engine for 10 min or more the next time you fly to make sure you haven't turned any thing off.
Happy Flying
Mark

Sent from my iPhone

[sadowin]

If you are running a paralell set up and have a failure of the diaphram in the vacuum pump the electric pump will send fuel through the pulse line as well. Mike S

[earthstaraircraft]

Have you ever herd of that happing?
What about the check valve in the vacuum pump?
Happy Flying
Mark
Sent from my iPhone