Good morning all. 30 hours on my 701 and loving it. Only concern is uneven fuel flow between tanks. Right tank ( passenger side ) seems to empty much faster than left. I do as many left turns as right and always try to stay straight and level :). Trying to keep it out of my head for cross country as left will show 1/2 to 3/4, and right will show 1/4 to 1/2. both caps are vented. dont want to be the moron that runs a tank dry. left is flowing just much slower. Any thoughts or is this normal?

Tom

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You might have to solder on some vent tubes that will stick into the airflow ,they might take a little tweeking to get them into the airflow that will balance the pressure better to get them to flow even ,not uncommon ,my old 150 cessna did the same thing!

My CH750 does the same thing. No idea why? I even installed different fuel caps and changed them from side to side.. no real understanding as to why this happens.

Thanks for the help eveyone.

Tom

lots of reasons, and all seem to have the same....

a) fuel lines are different lengths... thus different pressures.

b) air flow over the wings is different... thus changing the pressure at the cap

c) The aviation gods like us.... so they send us things to make us think

I am not sure if you run one side dry if the other will flow without sucking air, however, the easy solution is to put a tank selector in... then you choose, you monitor - but you also have to take the responsibility...see c) above!

I had to make a precautionary landing to get fuel when my passenger side tank was showing empty while the other tank was full.  Scared the crap out of me.  I had lots of fuel in the other tank but it did not appear to be flowing.  As mentioned above I installed simple shut off valves on each tank so if one tank gets low I can turn that tank off and force flow from the full tank.  Works great and relieves pilot anxiety.

 

Quality Planes told me the other tank would eventually feed fuel and you would not run out but I opted to make sure I had fuel flow.

I plan to use one of these valves at each wing roof to control wing tank fuel. Fuel selectors can have positions not in line with my psychomotor.

Thomas - You might notice that letting the tanks sit overnight that they level off with each other. After experiencing all this myself I have come to the same theory as Jonathan.

I'm not sure if this means anything or not but we have accumulated 7.3 hrs. so far with no fuel imbalance. After we herd that fuel imbalance can occur we were keenly aware of the fuel in both tanks and have watched it closely (longest flt. 1.7). The only thing that I can come up with that could be causing the fuel to flow evenly on our 701 is the vented header tank, the fuel lines are different lengths, and the vented caps are stock, we ran 3/8" hard line's from the wing tanks to shutoff valve to header tank to the firewall. Since the fuel is dropping evenly on both sides and our fuel system is not that different than any other 701 I am concluding the 3gal. header tank made a difference.
Dave
Hey Tom !
I too have experienced that same fuel level thing. And what I conclude is it is great. The low tank empties more completely then if I were able to control it. As soon as the low tank sucks air the flow instantly starts on the other tank and I now know that that tank is empty ! I fly my 701 long range up to Alaska in the summer. With a total of 40 gallons up in the wings. The fuel selector is inboard and outboard. I fly the outboards down first. Thanks David

Hi Thomas,

Got the same thing on my 701. Passenger side empties faster too. I went as far as shut it down to see if I would starve the engine. Not so ! The engine continued to run like a champ on the pilot side tank only as if nothing happened. I was told that this happens frequently. Looks like it's not a concern but still is strange. For me, I don't care anymore since I know both tank will run dry before the engine quits !

Regards,

Norm

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