Q: Fuel flow pulsing

[kentb]

IO-320 with 150 hr on tach.
The last flight I noticed the fuel flow started pulsing. After getting to 8500 ft I lean the engine for peak and got about 7.5 gph. It was than that I noticed the the FF was going from 7.5 to 9 gph. I couldn't time it very well while in flight, but though it was about 1 minute between pulses.
I thought the my exhaust valve might be going so I richened back up to about 8.5 to drop the EGT temp. I still saw pulses between 8.5 and 11 gph.

After I got home I dumped the data from my AFS 3500 (you gotta love these new engine monitor capabilities) and the pulses don't have much of a pattern. Anywhere from 50 seconds to 1:50.

I have always had a very steady FF varying by only .2 gph after the throttle is set. The fuel pressure is constant through out the pulse cycle. The red cube is located on the firewall and the electric fuel pump is off. The pressure sensor comes off the engine driven fuel pump as per the plans.

Is the FF sensor going bad or something else?

Kent

[Brantel]

Originally Posted by kentb

IO-320 with 150 hr on tach.
The last flight I noticed the fuel flow started pulsing. After getting to 8500 ft I lean the engine for peak and got about 7.5 gph. It was than that I noticed the the FF was going from 7.5 to 9 gph. I couldn't time it very well while in flight, but though it was about 1 minute between pulses.
I thought the my exhaust valve might be going so I richened back up to about 8.5 to drop the EGT temp. I still saw pulses between 8.5 and 11 gph.

After I got home I dumped the data from my AFS 3500 (you gotta love these new engine monitor capabilities) and the pulses don't have much of a pattern. Anywhere from 50 seconds to 1:50.

I have always had a very steady FF varying by only .2 gph after the throttle is set. The fuel pressure is constant through out the pulse cycle. The red cube is located on the firewall and the electric fuel pump is off. The pressure sensor comes off the engine driven fuel pump as per the plans.

Is the FF sensor going bad or something else?

Kent

Kent,

Mine started doing this on the way to Osh. What did you find on yours?