Abnormally High Fuel Flow Indication

[Steve Pierce]

Cathy and I attended a small fly-in last weekend hosted by a friend of our that has a really cool grass strip on a bluff over the Arkansas River just east of Tulsa. Had a great time playing on the sand bars on the river with some friends and at Sand Springs for a pumpkin drop and lunch. My Super Cub has an Electronics International FP5L fuel flow gauge which I really like in my Super Cub because I rarely fill the tanks up and 90 percent of my flying is local with 6-12 gallons of gas banging around on local gravel bars. The FP5L makes it easy to know how much fuel I have when the site gauges don't show anything in the 3 point attitude. It was 28 degrees the morning we left so I drug the airplane up to the fuel pumps with my small tilting trailer instead of starting it up in the cold. Our planned departure was several hours later. I topped off the tanks and took the airplane down to my main work hanger. Cathy flew the 2.5 hours up to the fly-in and informed me I had not programmed the fuel I had put on. I added some fuel at Sand Springs and guessed at what I had onboard, I didn't want to top off because we intended to do some more playing on the river and a full fuel load makes for poor performance and with the guys I was flying with I needed everything to my advantage because we tend to push the envelope a bit. The next morning we departed our friends strip and flew over to Okmulgee where I topped off and entered my fuel load. On the return trip we were paying for our 110 mph ground speed up seeing 55-75 mph ground speeds averaging 65-68 staying just above the tree tops most of the way so the ground speeds weren't even worse. I usually cruise at 2500 rpm and 7 GPH with the 8241 Borer prop, fuel flow goes up a gallon plus with a Sensenich 7258. I noticed the FP5L wa showng about 12 plus gallons an hour which got my attention. Monitoring the fuel gaug I could tell we were not burning that much fuel and could make the 3.5 hr trip home with one pit stop to pee.

I had to call Electronics International on another matter so I asked them what they thought of my abnormal fuel flow reading. the tech guy I spoke with thought I had inadvertantly hit a button wrong and changed the K factor on the fuel flow transducer when I entered the fuel on board. Yesterday after work I went out and checked the K factor and it seemed to be in line with the factory K factor, not almost double what it would be to show the fuel flows I was seeing. I called EI back and got a different tech guy and explained to him what was going on and he thought I might have some air bubbles trapped at the transducer. I kind of doubted this since it has worked flawlessly for many years. I hit the quick drain on the gascolator and say a lot of red liquid come out. Ah oh, I know what that looks like. I went and got my sump jar and sure enough I had some rusty water. Sumped both tanks and got a little more but most was in the gascolator. Let it sit a bit several more times until I got nothing. I took it up and stayed in the pattern and noticed my fule flow indications were back to normal. Called EI back and told them what I had found for future reference. I will for sure store it away for mine. Not sure where the water came from but have a sneaking suspicion it was last week when I pulled up to the gas pump and the airport manager said there was an issue with the pump on their fuel tank. He filled a couple of 5 gallon cans from the tank bottom and I checked it for water but found none but was prudent in sumping my tanks later. Lesson learned. Thought others might find this interesting and might helps someone else down the road sometime.

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[CamTom12]

Oh man, I wouldn’t have guessed at that solution. Glad you guys were safe and thanks for sharing. I’m filing that one away, too!

[Steve Pierce]

Drained the fuel tanks and carburetor bowl and cleaned the gascolator. Checked carburetor inlet screen and it was clean. Gascolator did it's job.
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[Tailwind_Fan]

Was the airport you stopped at Westport (4F91) by any chance? My uncle John used to keep his aircraft there.

Alana

[Steve Pierce]

Was the airport you stopped at Westport (4F91) by any chance? My uncle John used to keep his aircraft there.

Alana

We stopped in Healdon, OK F32 where there is absolutely nothing, not even a tree to hide behind. https://www.airnav.com/airport/F32 From previous trips across Oklahoma it seems the state comes in and builds airports, a taxiway and small ramp and that is it all over the state. this is one of many we have pit stopped at.

[Tailwind_Fan]

I’m sorry, I was thinking your friends airport was west of Tulsa on the Arkansas river. Which is a totally different place than where you picked up the rustic fuel.

[Steve Pierce]

The Rusty fuel came from my home airport when our airport manager ran out of fuel and filled my gas cans from the bottom of the tank. My friend's strip is east of Tulsa called Crowe Bar. We did visit Pogue airport at Sand Springs west of Tulsa.

[smcnutt]

Whenever we're fueling with a 5gal can we always use our filter/funnel
http://www.mrfunnel.com/Mr._Funnel/Home.html


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[Subsonic]

Called EI back and told them what I had found for future reference. I will for sure store it away for mine. Not sure where the water came from but have a sneaking suspicion it was last week when I pulled up to the gas pump and the airport manager said there was an issue with the pump on their fuel tank. He filled a couple of 5 gallon cans from the tank bottom and I checked it for water but found none but was prudent in sumping my tanks later. Lesson learned. Thought others might find this interesting and might helps someone else down the road sometime.

Steve, has EI gotten back to you and acknowledged that water in the gascolator upstream of the fuel flow transducer will cause an abnormally high fuel flow reading? It would sure be nice to hear back on that as I'm getting ready to order an FP-5L myself. Any idea how much water you drained out? Was the gascolator full? Thanks.

[Steve Pierce]

They said it made sense. Yes, the gascolator was full and then some. Took draining the sysstem twice and flushing everything to get all the water out. Good thing is that the engine never missed a beat.