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vshimsl(at)live.com
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 Posted: Sun Jan 17, 2010 11:24 pm Post subject: VDO erratic fuel pressure readings resolved |
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Hello C
This is followup to my inquiry about erratic high fuel pressure readings on my Dynon supplied VDO fuel pressure sender.
To recap C I would have normal readings for about thirty minutes then my fuel pressure would slowly creep up to 9 or 10 psi C then start bouncing around tripping my warning alarms (wakes you up quick).
I do not have fuel injection but in my archive and google search came across those with the same problem only with higher PSI readings.
Well C skipping the "I did everything perfect part" C the VDO fuel pressure sensor comes from Dynon with mounting tabs already installed. You assume as I that these tabs are a match for the aircraft quality slide on crimps. They apparently are not.
I removed and tossed these tabs and used a standard crimp connector instead (one with hole in it). Fuel pressure readings are now rock solid after two hour flight. Keep the nut and washers for use with the standard crimp though (I think they're metric) and do not tighten too much as I/you don't know if too tight will change the sensor resistance.
In my troubleshooting odyssey I used a scope meter (yes I got that desperate) to determine if any electronic device save the ignition was affecting the signal. The signal stayed rock solid. The radio would impress a millivolt high frequency signal across the sensor but there was no affect on the voltage or displayed PSI.
My take on the problem is that the tab crimp interface due to the mismatch would become intermittent when exposed to heat and/or vibration.
I relay all this to help others avert a very long C frustrating search. Frustrating in that most of us won't fly with erratic fuel pressure readings.
Now on to my tachometer accuracy problem.
Vinch H.
RV-8 'Flying'
N8432 - 24 hours
Hotmail: Trusted email with Microsoft’s powerful SPAM protection. Sign up now. [quote][b]
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rv8iator
Joined: 11 Apr 2006
Posts: 145
Location: Newberg, OR
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| Posted: Mon Jan 18, 2010 6:46 am Post subject: VDO erratic fuel pressure readings resolved |
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Vince,
Great sleuthing... And thanks for posting your method and result. Sometimes it takes a million dollar test to find a $.02 problem!
Chris Stone
RV-8
Newberg, OR
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C. Stone (RV8iator) |
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speedy11(at)aol.com
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| Posted: Mon Jan 18, 2010 9:58 am Post subject: VDO erratic fuel pressure readings resolved |
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Vince,
That is an impressive bit of detective work. Nice!
Stan Sutterfield
Do not archive
| Quote: | This is followup to my inquiry about erratic high fuel pressure readings on
my Dynon supplied VDO fuel pressure sender.
To recap=2C I would have normal readings for about thirty minutes then my f
uel pressure would slowly creep up to 9 or 10 psi=2C then start bouncing ar
ound tripping my warning alarms (wakes you up quick).
I do not have fuel injection but in my archive and google search came acros
s those with the same problem only with higher PSI readings.
Well=2C skipping the "I did everything perfect part"=2C the VDO fuel pressu
re sensor comes from Dynon with mounting tabs already installed. You assume
as I that these tabs are a match for the aircraft quality slide on crimps.
They apparently are not.
I removed and tossed these tabs and used a standard crimp connector instead
(one with hole in it). Fuel pressure readings are now rock solid after two
hour flight. Keep the nut and washers for use with the standard crimp thou
gh (I think they're metric) and do not tighten too much as I/you don't know
if too tight will change the sensor resistance.
In my troubleshooting odyssey I used a scope meter (yes I got that desperat
e) to determine if any electronic device save the ignition was affecting th
e signal. The signal stayed rock solid. The radio would impress a millivolt
high frequency signal across the sensor but there was no affect on the vol
tage or displayed PSI.
My take on the problem is that the tab crimp interface due to the mismatch
would become intermittent when exposed to heat and/or vibration.
I relay all this to help others avert a very long=2C frustrating search. Fr
ustrating in that most of us won't fly with erratic fuel pressure readings.
Now on to my tachometer accuracy problem.
Vinch H.
RV-8 'Flying'
N8432 - 24 hours
|
[quote][b]
| | - The Matronics RV8-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV8-List |
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