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xcflyn 06-11-2017 08:40 AM

dreaded fuel pressure and GRT Q/s
Hi my name is Dan. I am taking the first step (post one) in admitting I have a problem I cant control. Flying consumes my life, when I am away I think about it, crave it, find a way to get my High (generally near hypoxic at 14,500') and then repeat. Not sure what to do so I bought a second plane, a RV8 to try to overdose and put a end to this problem. Then I found vans air force where many have the same problem and learned to live with it - I am alive and living with my addiction and it does control me but I have accepted that I alone can not beat this, instead I will cure and cope in the cyber world with my fellow Vans addicts and life will be fine.
Then on a more serious note, I did buy this sweet RV to help my A-B flying at about 2x the speed of my Maule and a gallon or two less an hour while doing it. MY issues are more flashing lights then my last Christmas tree in 2002 (youngest grew up and moved out- I don't have to have a tree). My biggest gripe is now a low fuel pressure warning. Fine with Boost pump on (12+) but drops to 0-2 in flight. Book says .5 for the carbed Lycoming is fine. I have a GRT 2000/4000 and the sport. All show the same pressure so I am assuming it is the sender or actually a bad mechanical pump at 550hrs. The fact my gauges don't show in points makes it a little bit of a guessing game, like am I at .9 and it shows Zero ? The EIS I find a bit of a PIA to work with, much rather have a JPI any day. But the real question to this minute of your life I wasted having you read this. Is there a part number from Spruce or other of a sender that maybe works better and is more accurate ? I am going to do a pressure test with my A&P this week and see what there gauge shows compared to the panel just to be sure it is not the pump. Great forum, I really don't spend too much time on the forums as I have this thing called a J.O.B. that combined with my addiction and my W.I.F.E. doesn't leave me with a ton of free time. Cant remember what we did 25 years ago but it sure is nice to have advice at your finger tips.

TS Flightlines 06-11-2017 09:33 AM

Dan---its does sound like instrumentation, or the setting for the fuel pressure are off. BUT------before you spend alot of time flying (:D) trying to duplicate the problem, plumb in a known good mechanical gauge and check the pressure verses your GRT stuff. AND---just because you need something else to do, check the mechanical pump overflow tube for signs of fuel. HOPE not, but it wouldnt be the first time a pump would have a very small crack in the diaphragm and dump fuel, then stop.

Chances are its instrumentation, sender, wiring connections, etc, but check all of it.


Mike S 06-11-2017 10:15 AM

Welcome aboard!

Originally Posted by xcflyn (Post 1179636)
Hi my name is Dan. I am taking the first step (post one) in admitting I have a problem I cant control. Flying consumes my life

Dan, welcome to VAF.

BobTurner 06-11-2017 05:14 PM

In the EIS set up menu, there is a calibration factor, which depends on which model sender you have. First thing I'd check is, is that number correct?

David Paule 06-11-2017 07:01 PM

Dan, got oxygen? Out here it's worth its weight, cost and space.

That said, some friends and I customarily refer to flying as "oxygen deprivation therapy." Ignoring the fact that we all have O2.

RV-3B building
Cessna 180 flying

David-aviator 06-12-2017 07:27 AM

Welcome to the addicted aviator club. The RV-8 will go a long way to satisfying the hunger to fly...just pretend you are launching in a P-51 and have at it.

Can't help much with low fuel pressure light and carb, I have AFP fuel injection.

I do know about GRT system though, seems like your warning may be set a little high. It is pain in the butt but you can get in set-up page and change it.

dmaib 06-12-2017 07:58 AM

The GRT pressure senders have a history of doing just what you are describing.

scard 06-12-2017 08:04 AM


Originally Posted by dmaib (Post 1179796)
The GRT pressure senders have a history of doing just what you are describing.

Yep. Mine has been doing the same for longer than I care to admit... Negative fuel pressure sometimes, yet the fan keeps turning.

xcflyn 06-12-2017 08:36 PM

It sounds and reads like fuel pressure is one of the most common warnings we deal with in RV's. My guess is due to so many electronic gauges. My Maule is injected and has a mechanical gauge and no light- it can fluctuate a couple psi and I likely would not notice. I will be interested to see what the difference is when we test. I believe a sender is cheap, I am tempted to just buy one and put it on to see what happens ?

Deweyclawson 06-13-2017 06:08 AM

fuel pressure ground
I was told that the fuel and oil press senders are prone to errors and most of those are due to a poor ground. I was advised to, and did, solder a spade terminal tab to the outside of the sender and add a ground wire. No problems so far. (knock on head)

I did this before mounting them and before introducing any flammables to them.

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