Intermittent fuel flow from previously reliable system

[Guy Prevost]

I've got a fuel injected IO-360 (parallel) valve with a Red Cube transducer between the servo and the spider. My engine monitor is in my AFS 3500.

For the first 3 years, 350 hours my fuel flow readings have been spot on. For the last couple of months, my fuel flow reading will occasionally drop to zero. The engine runs fine, so I'm pretty sure it is an erroneous reading. To me it does not act like an electrical problem with the transducer, since turning on the boost pump and/or switching tanks usually solves the problem. Any ideas?

Guy

 

[cfiidon]

Theory

Guy,

My first thought would be an intermittent rotor caused perhaps by debris, or an internal (intermittent) failure. You could try removing it and flushing it out carefully. Might be worth a call to Electronics International for any info they might have.

Don

 

[Jamie Aust]

I had a similar problem with my red cube. I pulled it out and was to gently blow air past the rotor. It spun freely, so the only other thing It could be was a faulty wire from the red cube. A replacement fix the fault.

 

[rgrigson]

Ditto with the red cube...

My red cube was mounted between boost pump and engine driven fuel pump on an IO-375 (mounted on Firewall, wired to the Dynon D180). Fuel flow readings were very good for 2+ years, until recently when the fuel flow became erratic. The integration of fuel used over a flight became very inaccurate (the error showing more fuel used than actual). Removed the cube and found the rotor bearings very noisy - but still appeared to be balanced. Installed a replacement unit and all is well again.

Robert Grigson
Mill Creek, WA
RV-8 FB IO-375 Whirlwind 200RV