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Bizarre Fuel Pressure Readings

bill.hutchison

Well Known Member
I suspect I may have a fuel pressure sending unit getting ready to die, but not sure.

The EI FL-5 fuel computer has been a damned useful instrument, and the prior owner of my airplane really had it dialed in accurately. It is usually within 1/2 gallon of accuracy on everything. I've been cross checking it for 1 year and 100+ hours of flying and it's been stone-axe reliable.

Today I was be-bopping along at 7500' when I get a annunciator and a warning light for pressure. The numbers were all over the place, spiking and bottoming out every second.

The engine was running fine. Changes to the mixture didn't seem to have an effect. I turned on the boost pump and the numbers spiked even harder - bouncing between 30 PSI and then 160 PSI and then 40 PSI, etc...

Turned the boost pump off, watched it for a while. Didn't seem to have any pattern. Sometimes it would stabilize, sometimes it would just run amok.

There was NOTHING else to indicate the airplane had a problem. Everything was working as it should, which is why I suspect maybe the sender is going out?

So I took a video:

https://drive.google.com/file/d/1ggSJTDIT0aqS4KlHEeV5t2hWLhcZ65ib/view?usp=sharing

In every other respect, the engine ran fine, no issues, noises or anything. When I landed, no smells or fuel stains or spills.

Anyone ever see this before?
 
Bad ground on the sender, or (considering it was previously working just fine) more likely your sender has gone south.

Replace.

Carl
 
Bad ground on the sender, or (considering it was previously working just fine) more likely your sender has gone south.

Replace.

Carl

I called EI about a replacement and they suggested checking some wiring first because the behavior I saw was more consistent with an electrical issue than with a total failure mode. I might try that and see if there's anything obvious, otherwise, replacement will be done with the CI.
 
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