EI FP-5L erratic

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RichNY

Pre-takeoff checklist
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RichNY
I'm hoping someone else has had this happen and has info. At times the fuel flow goes to zero. It eventually starts reading but will incrementally go from 0, .4, 1.8, 4.2 etc then fall back to zero. Several minutes later, it'll start to rise and then read properly.
It does this every few hours and then will read properly for several hours. Anyone have this problem in the past?
Thanks
 
What's the "normal" fuel flow?

Mine only "wags out" when I'm dry tanking. Normal fuel flow is about 11GPH and it'll swing from 5 to 20 as I start sucking air when dry tanking.

Otherwise, it'll only swing back and forth about 0.5 gph. It used to not swing at all but rather landed on a fuel flow value and stayed there. I *assume* that it now swings a bit due to age/fuel residue/etc. :dunno:

I've had mine for 5 or 6 years now.
 
Hi Tim, normal fuel flow is 12 gph. My problem occurs at full tanks, half tanks etc. It reads solidly and consistently until it goes to zero. After a while it returns to it's consistent flow reading.
 
You might ping EI with this question. Their customer service is second to none.
 
RichNY said:
I'm hoping someone else has had this happen and has info. At times the fuel flow goes to zero. It eventually starts reading but will incrementally go from 0, .4, 1.8, 4.2 etc then fall back to zero. Several minutes later, it'll start to rise and then read properly.
It does this every few hours and then will read properly for several hours. Anyone have this problem in the past?
Thanks
Click to expand...

You need to provide a lot more info. For starters, what airplane? How long has it been going on? What's the wiring look like? Is it a new system or has it just stared doing it? Is the transducer installed per the EI drawings? Transducer position can trap air in it and cause problems.
 
timwinters said:
What's the "normal" fuel flow?

Mine only "wags out" when I'm dry tanking. Normal fuel flow is about 11GPH and it'll swing from 5 to 20 as I start sucking air when dry tanking.

Otherwise, it'll only swing back and forth about 0.5 gph. It used to not swing at all but rather landed on a fuel flow value and stayed there. I *assume* that it now swings a bit due to age/fuel residue/etc. :dunno:

I've had mine for 5 or 6 years now.
Click to expand...

Mine wags too,but the total counter is accurate, been happy with it so far, (used instrument and new transducer installed about 6 months ago).
 
I'm curious as to how the transducer was wired to the harness. I used "high temp" crimp-on gold plated .062 round contacts Molex connector.
 
I've been talking to the guys at EI and they are a good bunch. However, being my problem is very intermittent, I can't get to test the circuit when it fails. They said it's either a wiring issue or the transducer is starting to fail. That's why I was looking for some real life fixes that others have done.
The spade connectors at the transducer check out fine but they're sending me some round set screw connectors just to be sure.
The system has been installed for 8 years in a Bo with a 550.
 
Transducer is failing. It is a little wheel in the flow path and can get stuck as well as turning sluggishly resulting in the erratic readings.

I replaced mine this past summer for a similar problem.
 
Marauder said:
Transducer is failing. It is a little wheel in the flow path and can get stuck as well as turning sluggishly resulting in the erratic readings.

I replaced mine this past summer for a similar problem.
Click to expand...

Thank you. Your fuel flow readings went up and down and zero?
 
RichNY said:
Thank you. Your fuel flow readings went up and down and zero?
Click to expand...


Sorry Rich, I don't visit the site too frequently. Yes, I have had it read zero for a period of time and then come back. Also had it read low and fluctuating a bit (~1 GPH).
 
I should add that I was able to confirm this on two devices. I have the FP-5L and a JPI 830 sharing the same transducer. Both were showing the same thing and the JPI was actually recording the anomaly.
 
The transducer is that "red cube". Part number is FT60 and aircraft spruce has them.

The transducer works by generating 'pulses'. So a stuck vane like marauder mentioned would cause it as well as an intermittent connection. Try the new connectors first and trace things through first however. I never had an issue with my FT60/FP5L, but my UGB-16 was always having issues with broken/intermittent connections.
 
RichNY said:
I'm hoping someone else has had this happen and has info. At times the fuel flow goes to zero. It eventually starts reading but will incrementally go from 0, .4, 1.8, 4.2 etc then fall back to zero. Several minutes later, it'll start to rise and then read properly.
It does this every few hours and then will read properly for several hours. Anyone have this problem in the past?
Thanks
Click to expand...

Update. It was the fuel transducer. New FT-60 and all is well. Thanks all.
 
Glad to hear it was an easy fix...
 
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