VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #11  
Old 10-18-2013, 12:43 PM
tfarrell839 tfarrell839 is offline
 
Join Date: Oct 2009
Location: Canby, OR
Posts: 53
Default Prime the line?

Also, did you try priming the line? Crack the fitting with the fuel pump on and let some fuel flow out, taking with it the remaining air. I still can't figure out why this matters, both liquids and gasses should come up to the same pressure in the line, but it does seem to make a difference, especially on oil senders.
T
Reply With Quote
  #12  
Old 10-18-2013, 03:21 PM
Gagarin737's Avatar
Gagarin737 Gagarin737 is offline
 
Join Date: Mar 2009
Location: Netherlands
Posts: 663
Default

I think you have a point. After installing the new pump and Kavlico I primed the sender line. Results from the test run can be seen below. Pressure is ok. The flight thereafter was like the earlier graph. I also think its air in the pressure sensor line. But the first four flights pressures were solid (old sensor). The first low pressure indication was after about 10 hours. The sensor fuel line is a bit downstream and with that its strange air gets in (if thats the case).

__________________
PH-BZT

MyKitlog

Last edited by Gagarin737 : 10-18-2013 at 03:24 PM.
Reply With Quote
  #13  
Old 10-18-2013, 06:26 PM
MartySantic's Avatar
MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,390
Default

Quote:
Originally Posted by Gagarin737 View Post
A small piece of the graph from the flight I was talking about. First 0 psi indication at 600ft. Fuel flow stable. No drop in power. Third time in a row that I had these values during a first flight of the day. Still have to order a mechanical gauge.
I have seen the same. I have the old sensor and not the Kavlico. The low pressure condition alarm not not occur during runup, but, usually just after take-off. The condition persists for about 1 minute and then the indicated fuel pressure climbs back to normal. This condition does not occur on every take-off. Maybe 10-15% of the time. Never any engine hesitation. Fuel flow remains normal. I have yet to determine a cause. I have vented the fuel pressure sensor line.

Others that I have talked to have observed a similar condition. The alarm is observed only by those where the low fuel pressure alarm is set to 2.2 psig. If the alarm is set to 0.7 psig (as was the case with Van's earlier locked settings file), this condition is masked and the pilot never sees it.

Will be very interested to hear your results with the mechanical gauge. I've always wanted to try, but, have never taken the time to install the mechanical gauge.
__________________
Marty Santic ----- W9EAA
RV-12 N128MS ----- Now Flying
My RV-12 Build Log - http://www.martysrv12.blogspot.com/
Davenport, IA
Reply With Quote
  #14  
Old 11-08-2013, 09:51 PM
MartySantic's Avatar
MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,390
Default

Joeri.....

Any updates? Did you install a mechanical fuel pressure gauge?
__________________
Marty Santic ----- W9EAA
RV-12 N128MS ----- Now Flying
My RV-12 Build Log - http://www.martysrv12.blogspot.com/
Davenport, IA
Reply With Quote
  #15  
Old 02-24-2014, 12:29 PM
Gagarin737's Avatar
Gagarin737 Gagarin737 is offline
 
Join Date: Mar 2009
Location: Netherlands
Posts: 663
Default Update

Forgot to give an update.
I flushed all lines from tank to gascolator and installed the fuel lines from aircraftspeciality.
Pressure is fine since then. No explanation found for the low fuel press warnings.

__________________
PH-BZT

MyKitlog
Reply With Quote
  #16  
Old 02-24-2014, 03:39 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
Default

Quite likely that you have had some restriction in the old lines and with the engine hot during the climb and shortly in the cruise, the extra heat load causes vapour bubbles. You are sucking from a tank and up to the engine, all uphill in the climb.

Mogas has a high RVP, and in winter an extra dose of butane and the RVP is twice that of avgas. As you climb the outside air is at a lower pressure, the tank is lower, the pump is sucking harder and with any loops or restrictions vapour bubbles will form.
__________________
______________________________

David Brown

DYNON Authorised Dealer and Installer


The two best investments you can make, by any financial test, an EMS and APS!
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 09:16 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.