Online Community of Zenith Builders and Flyers
I have not seen detailed drawing but I can take pictures if you have specific questions. There are three things I learned with my installation that you may want to consider:
- I had to reposition the hose from the right tank to the gascolator that is in the bottom left of the fuselage. At first a long part of it was close to horizontal and could trap air, preventing the fuel in the right tank to flow. This happened while I was testing the engine so I moved the hose to have a steep angle.
- I later added a 1 liter in line tank, after reading a thread on this forum about fuel starvation in steep descent. Never had a problem but I wanted to be sure.
I positionned the fuel shut off valve so it sticks on my leg when it's in the OFF position. This way I am sure I do not forget to open it before flight.
Do you want pictures of some specific things?
Thank you for your generous offer. I would very much like to see how
you've engineered and installed your fuel system. It would be most helpful
If you would like to email these: firstname.lastname@example.org
I will look for more pictures, but I found two to begin.
On the first one you can see the fuel line connections to the tank. At the rear there is the fuel line. The white connector is a fail-safe quick connect. I have the folding wing kit and I thought I would be using it often. I was naive, I used it only once. In the center there is a fuel return line from the Rotax 912 with a low pressure check valve. I heard most people return it only to the gascolator, I went by the book on this one. Since that picture was taken I had to make an access hole to reach the fuel level sender, I had leak problems with these.
The other one shows the fuel line on the passenger side. The other hoses are for airspeed and AOA. The pilot side is similar, with the fuel return instead of the airspeed / AOA.
I will try to get a picture from behind the seats to show you how I installed the rest of the system.
Francois, these are tremendously helpful. Thank you.
If you find a few moments to take a few other pics that
would be even better. I notice you use small gussets
with rubber (silicone?) grommets to keep everything
properly oriented and routed.
Anything detailing the route under the seat, shutoff/selector
valve and thru firewall placement would be ideal.
I took three pictures.
686: Picture of the pilot side of the cockpit. The fuel pump was a requirement from the inspector, in my opinion it is useless for a high wings aircraft. The smaller 1/4 hose below the other is the fuel return line. The valve can be reached by the pilot with seatbelt on and sticks in my leg if I leave it closed.
690: That's the in line tank I was talking about. You can also see the fuel return line and the hose from the right wing.
693 : Position of the gascolator at the lowest point.
Feel free to ask if you have other questions.
Thank you, Francois.
I have my third 701 now and on all I used alum.fuel line and AN fittings from Summit Racing, from the tank I ran down the forward door post, down slope to fuel valve mounted in dash then down to gascolator, the lowest point in my systems is the gascolator on the bottom of the fire wall pass. side then alum. tube up to back of engine ,. thru a fuel filter in the fire sleeved hose to fuel pump.
Thanks Bob. It seems that the alum fuel line may be much cleaner than hose, also req. less maintenance.
I did mine like it sounds Bob did. I had trouble with the POS plans system; it wouldn't reliably gravity feed and I had the older Rotax fuel pump fail and it started quitting but had a b/u pump.mine comes outa the tanks to a facet pump on each side mounted above the pilot and pax head. then straight forward and down the w/s braces to a fuel valve on the dash then thru the firewall to a gascolator mounted on the f/w about a foot from the top and then forward to the pump and carbs. 3/8 AL tube/AN fittings except downstream of the gascolator and flex hose/fire sleeve forward from there.
I put the 2 pumps at the tank outlet cause on an aggressive light weight climb it's possible on my plane to get the rotax fuel pump very near or above the fuel tank level and if that pump quits it won't gravity feed and also the corner of the door post is a high spot that the fuel has to climb in a climb. I use the pump for the selected tank on takeoff. My valve is L R OFF so no transfer between tanks.
the 701 plans i have show fuel line schematics on sheets 7-WTO-1 & 2
So they do, Bruce. Thanks for pointing that out. Good to be on the same page now.
The OFF BOTH valve was a problem on mine. With the 2 tanks feeding at the same time thru the same valve there was the well known uneven feed. And since mine wouldn't reliably gravity feed thru the small, long line I had to depend on the fuel pump(s). So, if one of the tanks uneven fed down to empty my assumption had to be that the pump would suck air outa the empty tank. Before the mod to L R OFF I've landed well short of destination cause one of the tanks was nearing empty...I still had fuel in the other tank but had to consider it trapped fuel, thus the mod to what I did and no problems at all now. Wouldn't have it any other way ....total control over the fuel. I consider that a basic requirement to any fuel system. Course the PIC has to manage the tank selection bu I've never considered that a factor. But you may; your call as usual. IIRC some of the high wing Cessnas have the OFF BOTH system and no uneven feed problems that I'm aware of...I assume there is a balance line between the tanks to equalize the pressure and feed. Maybe somebody here knows for sure about that.
If I was planning to use the plans system, like Bob Jones, I would at least go to 3/8 AL line with AN fittings; that would probably reliably gravity feed. Mine had a bare trickle at the carb with the line detached and less than that with the tail on the ground and low fuel in the tank.
That's my experience with that YMMV as always do what YOU want