Fuel pressure issues causing Fadec Warning

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tafisama
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Fuel pressure issues causing Fadec Warning

Post by tafisama »

I am in now having Fadec warnings because of Fuel pressure issues.Today I had intended to fly over 200NM but had to turn back after 10mins.The engine was definitely running lean and pressure indicated 0psi on the VM1000.I manually selected BPS to on but the engine nearly quit making me quiclkly return it to Auto and pressure went up to 24psi and it improved running.I had to reduce rpm back to 2350rpm.Just about to get to circuit pressure dropped to 12psi.I was high enough to be able to glide onto the runway.As soon as I touched down Fuel pressure shot up to 34psi at idle which is where it normally is.I put the switch on off and taxied to the apron on the mechanical pump still it maintained 34psi.My Lame suggested something is wrong with the pressure compensating system on the mechanical pump.Later I went up to do some circuits and what I observed is on the ground the system runs very well with pressure reaching 53psi at 2400rpm.On climb between 500-650ft AGL the Fadec Caution comes on and on reaching circuit height when I powered back to 2350rpm the lights go off.This happened for the 3 circuits I did.At 2350rpm it was showing 115knts IAS.This has just started happening after completing the Annual Inspection.I am not too sure what we touched that was not supposed to be touched.

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paulmilo
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Re: Fuel pressure issues causing Fadec Warning

Post by paulmilo »

Cannot add anything useful I’m sorry, but I am impressed that you achieve 115 @ 2350.
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Re: Fuel pressure issues causing Fadec Warning

Post by N645XL »

Gasolator cleaned & installed correctly during annual? Fuel tank vent pipe unobstructed?

tafisama
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Re: Fuel pressure issues causing Fadec Warning

Post by tafisama »

Just an update,high fuel pressure is getting low.I am not sure if something is restricting fuel flow or its the mechanical pump not able to hold pressure.Today the engine was run on ground at WOT, fuel pressure was getting up to 45PSI.After adjusting, it got up to 48psi.Leaving the engine at WOT we observed pressure going down from 48 to 42 at which point the Caution light came on.A little longer the pressure became 00psi and the Warning light came on.Reducing the throttle to 1200rpm the pressure got up to 37psi.Could there be fuel restriction somewhere in the pipes???

Plan of action is to defuel the aircraft and remove the supply line all the way and check if there is anything in the line.We checked the bypass solenoid and it`s fine.When we removed the gascolator,it was aligned properly on refit.

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Re: Fuel pressure issues causing Fadec Warning

Post by N645XL »

I mentioned the fuel vent pipe check to ensure you weren’t drawing a vacuum on the fuel talk.

tafisama
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Re: Fuel pressure issues causing Fadec Warning

Post by tafisama »

N645XL wrote:
Wed Sep 02, 2020 12:41 pm
I mentioned the fuel vent pipe check to ensure you weren’t drawing a vacuum on the fuel talk.
Oh yes I checked the vent its not obstructed.The field guys from Continental have advised checking for blockage in the line from tank to gascolator,then to boost pump then up to the mechanical pump.The next stage will be fitting a mechanical gauge and compare the readings on the VM 1000.If the mechanical gauge shows that the pressure is indeed dropping then we will need to check the bypass solenoid if its not leaking or letting fuel past it.If all that comes out alright then the mechanical pump will need to be replaced.It`s going to be a week`s wait to get started as the LAME here is a busy man.

I thought the prop and annual were enough expenses but it now looks it was just the beginning.

Regards

Tafi

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Re: Fuel pressure issues causing Fadec Warning

Post by Bigphoto »

Make sure that you use a digital gauge that has been calibrated. When I had issues with my brand new engine turned out that my mechanic didn't have an accurate mechanical gauge and it wasn't right until we put a different calibrated gauge and turned out it was much lower.

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Re: Fuel pressure issues causing Fadec Warning

Post by tafisama »

Bigphoto wrote:
Fri Sep 04, 2020 7:49 pm
Make sure that you use a digital gauge that has been calibrated. When I had issues with my brand new engine turned out that my mechanic didn't have an accurate mechanical gauge and it wasn't right until we put a different calibrated gauge and turned out it was much lower.
Thanks a lot mate,I will advise my Lame.The biggest hurdle I have now is I cant run level 2 diagnostics on my laptop for some reason.That would have helped a lot.

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Re: Fuel pressure issues causing Fadec Warning

Post by ATCguy »

Interestingly, my XL2 recently started having a somewhat similar problem. Everything works fine during short trips but when you cruise for a long period of time, the fuel pressure slowly leaks down. After an hour and a half or so at cruise, the pressure will generally fall to 49 and then a caution light comes on. As soon as you pull the throttle back to descend, light goes off. Press the throttle back forward and receive full pressure.

Also, note from a previous issue with fuel pressure. When you connect a gauge directly to the system, you’ll get a different reading than the VM1000. That’s the PSIA and PSIG you’ll notice. The chart that shows fuel pressures at a given PSI uses the traditional gauge that you have to build with fuel line, a tee connector, and gauge.

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Re: Fuel pressure issues causing Fadec Warning

Post by tafisama »

A quick update to all.I had to run the diagnostics again.This time I started with just observing Live Data on the Laptop.My pump has gone very bad now.The fuel pressure is now not going above 43psi where as before it was going up to 49psi.With full throttle the pressure decrease to 38psi within 20seconds and rpm starts decreasing.Within 2 minutes pressure will be down to 22psi and the engine starts dying rpm down to 1200.Retarding the throttle to half way pressure jumps to 38psi and rpm goes up to 1800.We checked the fuel line and its clear of any restriction.So the pump is now being bench tested.All the four Fuel pressure sensors indicated the same pressure.

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