Help needed diagnosing high fuel pressure readings - Page 2

Scott Hersha · #11 09-25-2019, 05:55 PM

Steve,
I took your advice, and the advice of a few others, but your advice to bleed the fuel pressure sender (VDO) worked. I checked the grounds first and they were fine, then I pumped fuel through the line to the sender and re-attached it. Test flight showed completely normal pressures at all power settings and attitudes

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A couple days earlier, I re-plumbed my fuel lines and fuel filters between the tanks and the fuel selector. They were previously mounted at a steep uphill angle just before the selector. I mounted them a little further from the selector in the RV4 side wells and they are mounted flat, directly inline with the fuel feed line from the tank. My fuel flow was previously all over the place, I assume because of air being introduced because of the suction at the top of those fuel filters. Mounting them flat and a little lower seems to have solved that fuel flow indication problem. 3 flights so far - all is good...

Thanks gentlemen!

Mark33 · #12 10-05-2019, 05:27 PM

Okay guys, here?s an update to my high fuel pressure warning problem.

1. I checked the brand of fuel pressure sender that I have and it?s a VDO.
2. I checked my wiring for any loose wires, but everything appears good and tight.
3. I bled the line going to the sender, but the problem still persists.
4. When I turn the electric pump on, the pressure?s stabilize and the ?high fuel pressure? warning goes away.

I?m beginning to think that there?s maybe something wrong with the manual fuel pump.

Any more incite on what I should check next will be appreciated.

Hornet2008 · #13 10-06-2019, 08:29 PM

For mark33 responding from the other thread relating to fuel pressure. My problem was with a kavlico fuel pressure transducer. It intermittently told me I had high fuel pressure. On advice from jakej on this forum I unplugged the sensor from the Dynon Skyview and re-plugged it in and problem solved.

jakej · #14 10-07-2019, 02:38 PM

Mark,
The best advice I can give in your case is to replace the VDO unit with the Dynon supplied Kavlico one - they are very reliable

bruceh · #15 10-07-2019, 02:42 PM

I had a similar experience with intermittent high fuel pressure readings using the VDO senders to my Dynon Skyview.
I replaced it with a Kavlico sender and that fixed it. You'll need to add a +5V and Ground wire out to the new sender, and update the Dynon menu that you are using a different type of sender.

Mark33 · #16 10-07-2019, 02:53 PM

Thanks a lot guys!

bjdecker · #17 10-08-2019, 07:12 AM

Mark,

Maybe I've missed this - but what values is the Dynon reporting for Fuel Pressure, and what are the limits (alarms) set to?

Specifically what are the numbers when the engine is running at 1000 RPM, 2000 - 2700 RPM? What are the numbers sitting on the ground with the engine OFF and the boost pump running?

Also, do you have a restrictor installed in the 45? steel AN fitting at the Engine FUEL PUMP connection to the FUEL PRESSURE hose? A picture would be useful.

Thanks!

DGlaeser · #18 10-08-2019, 07:39 AM

I had a similar experience in my GRT equipped plane a while back. It happened just before OSH so I took the opportunity to quiz Greg - prez of GRT - about it. He said the VDO sensors literally have an arm that wipes across a resistor, and with time the resistor gets a wear spot at the normal reading position. So I replaced mine and all has been well since. He said the piezo electric sensors don?t have that problem - but they cost a lot more