The International Cessna 170 Association

Fairly new owner of 1955 170b on last flight of about an hour and half noticed the right tank was not drawing fuel despite selector on both. never had this problem before . any help in trouble shooting would be appreciated . Have put around 50 trouble free hours on her in last two months with no similar problem. Thx

Check to see if your fuel vent is free from mud wasps nests or other blockages ,and if you have a self venting cap. Have a close look at the cap and there is a orange rubber .'flapper' in it and has it perished and sealed up on its mating surface .i would also check that your fuel selector is actually turning when you move the handle to another position .plus then I would select the tank you want and do a fuel drain at the gaserlator. Does the fuel flow freely at that point . If all that fails have a look at the way you fly. I had a friend who had a new Cessna 182 with the same issues but when he flew he flew with one wing down all the time . I only picked up on that when we were flying together when he remarked that his AH needed attention. AND his control wheels weren't level either.

This is common behavior for these airplanes....although it sometimes is the opposite/left tank which appears to misbehave (probably because most 170s have both tanks with a vented cap.) See this discussion: http://cessna170.com/forums/viewtopic.php?f=24&t=1128

AFTER you do as suggested by ghostflyer (i.e., select your right tank only and confirm the gascolator will still drain fuel freely from the right tank...then test again to compare with left tank only...then again with both)... consider that BOTH tanks actually feed the engine but one tank is refilling the opposite tank via the overhead vent-line, thereby keeping your right tank filled.... until sufficient ullage (the air above fuel in the tank) is sufficiently large to create a differential atmospheric pressure between the two. At that point the full/right tank level will also drop.

You can "trick" the system by taking off/landing on BOTH always... but after a safe altitude, select your right tank for about 30 minutes, then re-select BOTH.

OR... you can ignore it.... and you'll see after a couple hours that both tank levels are falling. The difference in lateral balance is unimportant.

My tanks draw unevenly too, about 3 gallons difference in 25 used, but your situation seems much worse. Drawing all or mostly from one tank is worth investigating.

Try swapping fuel caps.

thank you very much for the help I will look into it as suggested,,,,,and let you know

Dpetert wrote:thank you very much for the help I will look into it as suggested,,,,,and let you know

I have sent you (in an email) an extensive article on this subject. Unfortunately it is copyrighted so I cannot post it here.
George

I think we got ahead of ourselves here and forgot to welcome this new owner to the fold. Thanks for asking the question, welcome to the association and please post a pic of your plane if you can.

Thanks Jim for welcoming me to the group. I have learned a great deal about my 170 reading the forums. Cant figure out how to post a picture of my bird.
ie the uneven fuel flow was secondary to a problem with my vented cap it seems better now. THX again Triv

Dpetert wrote:Thanks Jim for welcoming me to the group. I have learned a great deal about my 170 reading the forums. Cant figure out how to post a picture of my bird.
... Triv

Here's a tutorial by Bruce: http://cessna170.org/forums/viewtopic.p ... ost#p78134

Every time that I have heard this complaint, it has been the ball not centered. Fly it normally and look at the ball. If it is even a quarter ball one way , push rudder and make it half ball the other way. Fly for awhile and see if problem goes away. Every time. Andrew