Fuel flow on takeoff!

[Wayne Braden]

I have O-360 A1A, fuel flow on T.O. Shows about 14 gal according to the Shadin fuel flow. I believe this is low, TGT stays the same and during leaning does not move much. Cruise at 5500' I need about 10.5 gal to keep eng running smooth. That seems high... For that Alt. I have looked at the book for the flows, 2400/23" shows about 8.5 gal. I have checked for induction leaks and found none. Has anyone had a similar issues. I had a JPI in my super decathlon and it was right on, TO 18-19 GPH for same engine, but fuel injected! Some times to much info is dangerous, I have little faith in the Shadin!
Thanx

[N3322G]

Wayne, Have IO320s so can't compare fuel flow but will say the Shadin in our Twin is the only fuel flow STC'd. Since day one in a prior version in 1979, the fuel flow has been 100% accurate - that' isn't to say you might not have an issue but thought you'd appreciate a positive reference for the Shadin.
BTW at 700' 70 degrees F, we do 15.9 for each engine.

[md11flyer]

Wayne: Fill your tank to the lip, then reset the shadin. Fly for an hour and note how much fuel it said you used. Then top the tank back to the same level. If your Shadin is out of calibration it will show up after this test.
Have you changed the transducers recently? maybe the K factor was inputted incorrectly into the Shadin.
Like Pat,my Shadin is bang on.

Gary

[md11flyer]

Wayne, as a follow up, its seems to me with what you are describing you might have a carburetor problem.
The fact that there is not enough fuel going through it during takeoff and the fact you can't get the engine to lean out to normal figures sounds like you might have some restrictions in the metering within the carb.
You might want to have the screens checked and then if you find debris, find out where its coming from and then have your carb gone over with an IRAN.
If the carb is good and the fuel flow was normal during takeoff (bad info from the shadin) Your leaning problem could be related to poor ignition. Check your plugs for good resistance and cleanliness. ( Is the timing good?)
If you had an engine monitor it would tell you exactly what it was. Ask for one for your birthday, they are worth their weight in gold as far as I am concerned.
Good luck,
Gary

[James Turner]

Hi Wayne,

I have a -180 with the same O-360 A1A and a JPI930 installed.

On take off I see ~20gph. During climb ~17 reducing to 15 gph; and in cruise, leaned at ~5500' the FF would be in the range of 9.5-10 gph depending on a number of factors. At 10,000' FF is down to 8-8.5 gph.

Recently I installed a full set of Tempest fine wire plugs to try to smooth out the engine at higher (75%) power and to improve the leaning performance and in short it has been a huge improvement. Running at 75% 2300rpm is now very smooth and I can lean to 35deg Lean of Peak (leanest cyl is 35 deg LOP, richest cyl is peak). I also find that in ISA- temps a little carb heat helps to maintain smooth running at lean mixtures.

James.

[Steve Marcozzi]

Wayne,

Just checking in and read your post. I have a 180 with a Shadin Digiflow and see similar numbers. Cruise (5-6000') at 23/24 is ~10.5gph (75%) and 22/23 is ~8.9gph (65%). I find the Shadin to be accurate at refueling as well usually showing .6 or .7 gallons more than pumped on a 3hr leg when I top off.

Steve