AGLyme Posted August 20, 2020 Report Share Posted August 20, 2020 https://youtu.be/ot8UZT9ulok Video above of the dancing fuel gauge... Folks, We thought we had it solved... and I was going to post the story for some other pilot to read in the future to learn from my challenge. Anyway, we are going to the next level of review... First, the engine runs perfectly fine. Always has over 150 hours -- and it did today. The problem is the (Dynon) fuel pressure gauge. It started reading "low green/high red" when the Aux fuel pump was turned on... then, eventually, the needle would settle back down to high green with the Aux fuel pump on. Once the Aux pump was turned off, the readings were normal. Then starting recently, I saw "low green/high red" range readings... which is the opposite of the old issue... then, as I was flying, the needle went highest red there is... again, engine ran fine... but it game me a scare. Coincidentally, Tom P was at my field and saw me land and said "nice landing"... Tom never says nice landing...; )... and I told him I landed long, but I didn't want to risk going around because God forbid I had a legit fuel pressure issue and not a bad gauge. Arian drove to my field and replaced the Dynon sensor... and this is after replacing the fuel filter and cleaning the gascolator at Annual the week before... I didn't know this, but Arian had to "replace" the Dynon sensor with the new one in the Dynon software... Part #, etc... so the Dynon can work with the new sensor. I thought that was interesting. Anyway, Arian hit the Aux power and the new sensor worked normally... we didn't start the engine. I started the engine today and now the needle is dancing all over the place... see the video... evidently it is unusual for (Dynon) sensors to fail, so this is a mystery. Arian is making calls and performing an investigation into the next step. We are going to attach a mechanical fuel pressure gauge and check those readings... Any ideas would be appreciated. I am hoping to get my bi-annual and get to the Airshow in Illinois... Love Arian, smart guy, hard worker... Thanks in advance... Andrew Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted August 20, 2020 Report Share Posted August 20, 2020 This could easily just be a loose wire. You can install a mechanical pressure gauge in line for a test and if it reads the steady then you have a loose wire. You've already done some of the other trouble shooting. Quote Link to comment Share on other sites More sharing options...
AGLyme Posted August 20, 2020 Author Report Share Posted August 20, 2020 Let’s hope that’s all it is... thx RL... will be doing the mechanical gauge shortly, will report back. Quote Link to comment Share on other sites More sharing options...
Philip Welsch Posted August 20, 2020 Report Share Posted August 20, 2020 I have been having a similar issue (2008 LS, 1100 hrs.). Cleaned VDO fp sender and fuel line to it - no change. Replaced sender - no change. Relocated sender - no change. Generally 5.0 to 3.2 psi to about 1500 agl then reduction to as low as 2.2 psi. Returns to 4.0 to 5.2 after a few minutes where it may remain for several hours. Yesterday there was a new trick. After an hour or so in cruise flight (4.0 - 5.2 psi) the fp began increasing eventually to 7.2. It varied from 4.5 to 7.2 for the next 20 minutes. Quote Link to comment Share on other sites More sharing options...
Philip Welsch Posted August 20, 2020 Report Share Posted August 20, 2020 Continuation: During reduced power descent fp returned and remained 4 - 5. Fuel flow during all of this remained normal (5.9 to 6.1 gph in climb and 4.7 to 5.1 cruise (5100 rpm). Never an indication of an engine issue except for the fp. Aircraft attitude changes nothing. The fuel pump has been discharging some small amount of oil during most flights. Brian Carpenter (Rainbow Aviation) indicated in SportAviation, Sept. 2018 oil leakage was an indication of fuel pump Garlock seal failure. Thie pump is two years old. I have a spare pump and that may be my next attempt to resolve the issue. Quote Link to comment Share on other sites More sharing options...
AGLyme Posted August 20, 2020 Author Report Share Posted August 20, 2020 After a variety of RPM levels, and, switching the aux fuel pump on and off... the mechanical fuel pressure test proved that the engine is ok... it's probably an electrical issue as Roger suggested. Will leave it at the shop tomorrow... and Arian will go through the wiring, etc... (PS, the mechanical pump was plugged into the fuel line in the engine compartment and the gauge was tethered to a fuel line and we brought it into the cockpit while started. Quote Link to comment Share on other sites More sharing options...
AGLyme Posted August 21, 2020 Author Report Share Posted August 21, 2020 Fixed. Arian fiddled with the connectors. Back in business. You were right RL. Quote Link to comment Share on other sites More sharing options...
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