Fuel tank inbalance?

PGT

Well-Known Member
Equal weight in both pilots, after 1.5 right side had more gallons more than the other.

Just me, after a 200+ nm journey left tank had 1gal and right had 7. Same trip going the other way left had 2 and right had 4 gallons left. This is a C152 mind you that burns 5.5-6 gal an hour.

What could be the issue?
 

ppragman

FLIPY FLAPS!
Equal weight in both pilots, after 1.5 right side had more gallons more than the other.

Just me, after a 200+ nm journey left tank had 1gal and right had 7. Same trip going the other way left had 2 and right had 4 gallons left. This is a C152 mind you that burns 5.5-6 gal an hour.

What could be the issue?
Misfueling by 2 gallons, also, with the ball centered, the airplane may still be in a slight sideslip (look at what the ball does on the ground) which could possibly cause a slight fuel imbalance, further, you could have a slight restriction in the fuel line from one tank to the other, or the line on the right side may be shorter than that on the left (i don't know the mechanics of the 150, haven't helped on an annual in over a year).

However, perhaps the most likely reason is this. You had a head wind going out, and tail wind coming back. Both times may have been a coincidence. This is why I just use the "run a fuel tank dry" method. Outbound, run the right tank dry, if you're not half way there, divert. (And I don't mean go back the airport of origin, just divert, rather than trying to second guess the fuel system).
 

Stonefly

New Member
Equal weight in both pilots, after 1.5 right side had more gallons more than the other.

Just me, after a 200+ nm journey left tank had 1gal and right had 7. Same trip going the other way left had 2 and right had 4 gallons left. This is a C152 mind you that burns 5.5-6 gal an hour.

What could be the issue?
The fuel tank vent is on the left in Cessna's. This causes fuel to flow at a slightly greater rate out of the left tank. This is especially true if you don't have a vented fuel cap on the right. I'd have to go digging through boxes to find a Cessna POH, but I believe it's recommended that you switch tanks (not run on both) over 5000'.

Nothing is wrong, it's just the design of a Cessna!
 

PGT

Well-Known Member
You can't switch tank feed in a C152, it's either on or off.

I was worried about running the tank dry might cause the engine to sputter and/or possibly quit on me.
 

ppragman

FLIPY FLAPS!
You can't switch tank feed in a C152, it's either on or off.

I was worried about running the tank dry might cause the engine to sputter and/or possibly quit on me.
Ah yeah, you're right, its been awhile, as for other birds, there's nothing wrong with running the tank dry, it may sputter, and it may quit, but when you select the opposite tank it will fire right back up.
 

Stonefly

New Member
You can't switch tank feed in a C152, it's either on or off.

I was worried about running the tank dry might cause the engine to sputter and/or possibly quit on me.
Oh yeah, it's been awhile since I've flown a 152 as well! Still, everything else in my post remains the same. The fuel will drain from the tank with the least resistance. That will be the tank that has less vacuum (the left one), until it's dry. Theoretically the head-pressure in the fuller tank (the right one) will then continue to feed the fuel system.
 

ppragman

FLIPY FLAPS!
Oh yeah, it's been awhile since I've flown a 152 as well! Still, everything else in my post remains the same. The fuel will drain from the tank with the least resistance. That will be the tank that has less vacuum (the left one), until it's dry. Theoretically the head-pressure in the fuller tank (the right one) will then continue to feed the fuel system.
Theoretically.

On 206s/207s btw, you have 2 vented fuel tanks. If I remember right, the Caravan's vented in the same way. Which, as far as I'm concerned, is awesome. Anytime you have the opportunity to have 2 or more completely separate sources of petroleum, fuel planning is much easier, and its also easier to fly without holding constant pressure on the yoke. I love fuel based aileron trim.
 

SpiraMirabilis

Possible Subversive
Which way did you turn while taxing to the ramp? A sudden (or sometimes even not that sudden) turn can cause fuel transfer between tanks in a 152. Was where you parked 100% level?
 
R

Roger, Roger

Guest
I have heard from people with lots of 150/152 time that it is possible for the engine to quit/hiccup when one of the tanks runs dry, even if there is plenty in the other. Something to do with not having a reservoir or feeder tank after the selector. Can anyone confirm this?
 
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