First, Build a Shed

[Cherrybark]

Had a text exchange with Eddie this afternoon and he cleared up the purpose of the plumbing loop on the Fine Filter Sub-Assembly. He did suggest I double check so I'll post my understanding. The "Out" line from the dual fuel pump box runs to the fitting marked XB on an aluminum block. That block has three other outlets, the most obvious being a location for my fuel pressure sensor. A second fitting supplies fuel to the large, "Gemini capsule" shaped can on the upper part of the U-shaped loop. This is a fine fuel filter and needs to be correctly oriented. The third fitting supplies a "pop-off" valve set at 17 PSI. This is also a directional element. For the life of me, I couldn't understand the point of this loop or what the 17 PSI valve was all about until Eddie explained. Should the fine fuel filter become clogged, fuel pressure will eventually build to 17 PSI and the pop-off valve will open and continue supplying fuel to the engine. In summary, there are two possible sources of fuel to the T fitting XG which is were the fuel line to the engine rail is connected.

Just to double check my work, and remembering that engine and airplane references are based on the view from the pilot's seat, I ran a fuel line from the XG T-fitting to the rail on the right side of the engine. Is this correct?

Made a quick visit to the hanger today but no time to work on the plane.

• The 17-PSI pop-off valve is installed backwards. At least, my hand drawn flow arrow, points towards the aluminum block. I thought reversing this would fix any fuel flow problem then realized it's very unlikely the brand new, fine fuel filter is clogged. Obviously the valve needs reversing. And I'll examine it closely to double check that my arrow points in the right direction.
• The header tank return line check valve, located under the center console, is oriented correctly. This unit has a clearly marked flow direction as, in my opinion, all of these units naturally should.

This weekend I'll have a mechanical fuel pressure gauge available for testing. I'll measure the pressure at the pump outlet and at the engine. it would be great if a simple plumbing restriction was the issue. If the engine is not running, does fuel flow freely to the header tank return line? Or does PSI just build to the pump limit at the engine input since the injection isn't running?

If there is 40 or so PSI at the input to the engine, I'll be jiggling ignition wires, calling Kitfox, and wondering what to look for next.

Oh, first one to fly into East Texas and point to the problem, get's a free Combo Plate at the Purple Pig BBQ joint just down the road!

[efwd]

Sorry Eric, I didn't mean to seem snippy. I was just trying to convey some of my frustrations with the sensitivity of the 912iS. The computers are interrogating at some unreal rate and if there's a slightest jiggle in a connector at the same time as the interrogation, BINGO a Lane Light will come on. The computer will report a mis fire immediately. Speaking of that. Carl, are you showing a code on the gadget you have in your panel? Let us hope that simply flipping the valve works. Even if we don't know the physics, we will know what symptom it presents when installed backwards.

[Cherrybark]

I'll measure the fuel PSI at the engine before and after reversing the pop-off valve. I assume the valve is having no affect since fuel should flow freely through the fine filter canister. But it's certainly worth measuring both ways.

[Eric Page]

Sorry Eric, I didn't mean to seem snippy.

No worries, Eddie!

[Cherrybark]

One of the nice things about small airports, particularly residential airports, is the depth of expertise and general willingness to help you find in the locals. Or maybe it's that retired, or soon to retire, people are easing into the "busybody" stage of life.

I kept the hanger doors close while configuring the red, yellow and green color band ranges on the Garmin engine instruments. It was nice to sit in the airplane and learn a bit more about the avionics. With that done, it was time to open the doors and roll the plane out to the grass. Today's job is figuring out why the engine won't run smoothly and the inevitable sprays and small streams of gasoline will make less of a mess on the grass. First task was to plumb a mechanical fuel pressure gauge where the supply line connects to the engine rail. Easy enough. Almost disappointingly, fuel pressure is normal on both fuel pumps. This small project attracts my first neighbor and he's just in the the nick of time. While there might be sufficient static pressure, perhaps the flow is only a trickle. Helping hands point the supply hose at a 5-gallon bucket while I man the cockpit switches. Success! I mean, damn. There is plenty of fuel flow at pressure. This isn't going to be a simple problem.

Now we have two guys holding wrenches and looking at an airplane with the cowlings removed. That will attract a crowd quicker than turning on the high school stadium lights on a Friday night during football season! The next four "guests" are all pilots and one has experience with the carb version of the 912. We jiggle wires, talk about throttle position sensors, and I explain just how little of the actual engine is "assembled" by the builder. Honestly, I'm about average when it come to airplane systems and these guys have been playing with flying toys almost all their lives. However, an injected 912 iS is new to our field and our small group is quickly reduced to, "Better ask Rotax". People drift away, and I'm left with my original neighbor when another golf cart arrives. This is a fellow EAA member who I know as "the guy who has a T-Shirt printing business with his wife". Both are wonderfully pleasant people but we've never talked airplanes. He is curious about the problem, asks a few knowledgeable questions, drops comfortably into jargon such as "ECM", and explains he is retired Air Force with a career in electronics and power plants. After confirming fuel flow, pressure, proper ground, and the problem of rough running, he suggest the problem is that a perfectly good engine has been laying around idle for 2+ years and just needs to be run a bit. We pull the lower plugs to check for standing oil then, under his direction, I flip switches and press the starter while he stands by the engine and has control of the throttle. In all of the jiggling, there are a few seconds of smooth running then the engine roars to life. He gives me a chopping motion and I kill the engine. We have oil pressure, fuel, and electricity and he's completely convinced the engine just needs to be run for awhile to blow out the cob webs. Everyone stands back, the engine is started, and we run it at various RPM while waiting for oil temp to get in the green. After warming up, idling is beautifully smooth and the gauges are all in the green. Lane B does flicker intermittently but that's a simple problem to track down now that the engine is running.

Monday, I'll drop the DAR paperwork in the mail and schedule an inspection. There is the never ending list of small maintenance items every plane has, but that gives me something to do while waiting for inspection. I wouldn't fly behind this engine yet. But, over the next few days I'll run it several times and build confidence.

[JMH]

I’m glad you got if figured out. Good luck with DAR. Before I called my inspector, I invited my EAA chapter members for a visit and asked that they look my airplane over and report anything that they thought was an issue. They were glad to help and it was like I had challenged them to find something wrong. Needless to say when my DAR visited he didn’t find any loose jam nuts.

John

[bumsteer]

Carl

Got my fingers and toes crossed. Good luck!!!

Rick

[Flybyjim]

Hi Carl,

I have been following your thread here, I am glad for your new success with the SI. Small airports are fine places to hang out even when you think you know most folks there we really don't know what they know. Every day we get a new chance to learn.

Jim

[bbs428]

That's great news Carl. I couldn't think of a more appropriate Christmas gift for you.

All the best with your upcoming DAR visit.

[tracstarr]

Great to hear things seem to be better with the engine. I've yet to get my startup as the weather has been bad and other things got in the way. Also wasn't able to ask my buddy about it for you either.
Have you managed to setup everything on the G3X for the Rotax? If not, here's what I've done....

When you startup make sure you enter configuration mode on the G3X. Once up, I turn on my backup power and switch on lane one A and B so that the engine readings come alive. On the main system info page you should see under the device list FADEC 912iS_Sport with a green checkmark. It will be and X if you don't have lanes on. You should see all of the details listed on the right page. It's also a good spot to look at throttle reading to see what % it's reading as you move it in and out - that way you can verify that's working since you mentioned some concerns there.

Next head on over to the GEA24 setup page. Make sure cylinder head temp is disabled as it's not required. You should see FADEX for the next 4 items, then your fuel pressure and FADEC on RPM1. Scroll down to Pos6/GP 6 and configure it to coolent emp (fadec) and then Pos7/GP7 configured to manifold air temp (FADEC). I think those are the key items from the FADEX inputs.

I've put in for my final inspection as well - likely first thing in the new year. Lots of little things to clean up. A few small deficiencies I've found but nothing major.