Low fuel pressure... again

Any DA40 related topics

Moderators: Rick, Lance Murray

User avatar
ThomasD
3 Diamonds Member
3 Diamonds Member
Posts: 166
Joined: Thu Jan 20, 2011 9:53 pm
First Name: ThomasD
Aircraft Type: DA40
Aircraft Registration: N215DS
Airports: EGGD
Has thanked: 1 time
Been thanked: 16 times

Re: Low fuel pressure... again

Post by ThomasD »

Lance,

Thanks for the tip, will do

Tom D
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
Posts: 1575
Joined: Tue Jul 06, 2010 10:09 pm
First Name: Rick
Aircraft Type: DA40
Aircraft Registration: NONE
Airports: KROA
Has thanked: 107 times
Been thanked: 297 times

Re: Low fuel pressure... again

Post by Rick »

Sorry to revive an OLD thread, but my DA40 has just started having this problem now. Fuel pressure drops to near-zero for a second or so, then returns to normal, setting off the LOW FUEL PRES alarm. Adding the backup pump has no effect. No apparent effect on fuel flow or engine performance.

What's the concensus among those of you who replaced your fuel pressure sensor - did that solve your problem or not? The two competing theories posed in this thread seemed to be either a bad sensor or blockage in the tank. In my case, I have the issue on both sides, and after 4 years of NEVER seeing this problem, it now happens almost every flight, so for me it's not "normal" as Diamond suggested. I'm ready to swap the two pressure sensors as a test, but I wanted to see what conclusion those of you who have "fixed" this problem in the past came to...

Thanks!
Roanoke, VA (KROA)
User avatar
ThomasD
3 Diamonds Member
3 Diamonds Member
Posts: 166
Joined: Thu Jan 20, 2011 9:53 pm
First Name: ThomasD
Aircraft Type: DA40
Aircraft Registration: N215DS
Airports: EGGD
Has thanked: 1 time
Been thanked: 16 times

Re: Low fuel pressure... again

Post by ThomasD »

I had a similar issue, investigated the wiring (pulling connectors on/off) - not keen to replace the sensor considering the price - and the problem went away and has never come back.
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
Posts: 1575
Joined: Tue Jul 06, 2010 10:09 pm
First Name: Rick
Aircraft Type: DA40
Aircraft Registration: NONE
Airports: KROA
Has thanked: 107 times
Been thanked: 297 times

Re: Low fuel pressure... again

Post by Rick »

ThomasD wrote:I had a similar issue, investigated the wiring (pulling connectors on/off) - not keen to replace the sensor considering the price - and the problem went away and has never come back.
Good suggestion, Thomas - I'll try cleaning up the connectors first. I just invested in some Stabilant, so this would be a good application for it!
Roanoke, VA (KROA)
User avatar
kevingab
1 Diamond Member
1 Diamond Member
Posts: 9
Joined: Mon Dec 03, 2012 4:22 pm
First Name: Kevin
Aircraft Type: DA40
Airports: KGLS KEFD
Has thanked: 2 times
Been thanked: 2 times

Re: Low fuel pressure... again

Post by kevingab »

Rick,

I swapped the oil and fuel pressure sensors a while back and that solved the issue. Cleaning the contacts is a good first step.

Good luck!
Kevin
User avatar
blsewardjr
4 Diamonds Member
4 Diamonds Member
Posts: 485
Joined: Tue Jul 26, 2011 11:19 pm
First Name: Bernie
Aircraft Type: DA40
Aircraft Registration: N377DS
Airports: KCHO
Has thanked: 118 times
Been thanked: 146 times

Re: Low fuel pressure... again

Post by blsewardjr »

So apparently I've now joined this low pressure club. After years of rock solid fuel pressure readings, in the last two flights, I've had the pressure go down to as low as 18 (so no warning) then back up to 24-26 which is where it usually is. On the first one, the pressure was 15 upon startup then gradually climbed up to 24. At first it appeared that the electric fuel pump didn't make a difference, but on the second flight when I added the electric fuel pump and waited about 3 seconds the reading went back to normal. This happens almost exclusively in climb. The engine does not change power or fuel flow. My mechanic thinks it may be a failing engine-driven fuel pump because it improves when I add the electric fuel pump but after reading these posts it may be the vapor issue mentioned by Diamond. Unfortunately, unlike most of you I have a 2003 with the VM 1000 engine monitor so no data downloads. I'm reluctant to change out the engine driven fuel pump on a 600 hour engine (Aviation Consumer says engine fuel pumps are supposed to last until TBO) but in an abundance of caution I probably will do so. Any suggestions regarding this particular set of facts would be welcome. Thanks.
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
Posts: 1575
Joined: Tue Jul 06, 2010 10:09 pm
First Name: Rick
Aircraft Type: DA40
Aircraft Registration: NONE
Airports: KROA
Has thanked: 107 times
Been thanked: 297 times

Re: Low fuel pressure... again

Post by Rick »

I'm sorry for not posting back about this. A couple of months ago, my fuel pressure reading became even more erratic, both high and low multiple times on every flight. I finally disconnected the plug and applied Stabilant to the connector, and my fuel pressure has been rock-solid ever since. My mechanic said he has changed the connector on several DA40's to fix this problem, so I ordered a new connector, but I thought I'd try the Stabilant first, since the connector is so easy to get to. If the problem comes back, I'll probably install the new connector next.

I wonder if those who had success by just swapping the sensors, actually "fixed" the problem by simply removing and reconnecting the plug, thereby reestablishing a good connection again...
Roanoke, VA (KROA)
User avatar
Lance Murray
5 Diamonds Member
5 Diamonds Member
Posts: 1163
Joined: Tue Jul 06, 2010 11:25 pm
First Name: Lance
Aircraft Type: DA40
Airports:
Has thanked: 7 times
Been thanked: 118 times

Re: Low fuel pressure... again

Post by Lance Murray »

I am not familiar with Stabilant. What is it?
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
Posts: 1575
Joined: Tue Jul 06, 2010 10:09 pm
First Name: Rick
Aircraft Type: DA40
Aircraft Registration: NONE
Airports: KROA
Has thanked: 107 times
Been thanked: 297 times

Re: Low fuel pressure... again

Post by Rick »

Lance Murray wrote:I am not familiar with Stabilant. What is it?
It's ... expensive! But seems to be worth it, based on the product reviews, and the limited experience I have with it. You can Google "Stabilant 22", but here is a link to some good information...

I expect the 5ml bottle (under $40 - a bargain at only 0.04 aircraft units!) will last my lifetime.
Roanoke, VA (KROA)
User avatar
Lance Murray
5 Diamonds Member
5 Diamonds Member
Posts: 1163
Joined: Tue Jul 06, 2010 11:25 pm
First Name: Lance
Aircraft Type: DA40
Airports:
Has thanked: 7 times
Been thanked: 118 times

Re: Low fuel pressure... again

Post by Lance Murray »

I doubt it is your fuel pump but your vintage airplane had a MSB on the fuel pump requiring replacement with new based on the serial number of the pump itself. Have your mechanic run the serial number of your pump.
blsewardjr wrote:So apparently I've now joined this low pressure club. After years of rock solid fuel pressure readings, in the last two flights, I've had the pressure go down to as low as 18 (so no warning) then back up to 24-26 which is where it usually is. On the first one, the pressure was 15 upon startup then gradually climbed up to 24. At first it appeared that the electric fuel pump didn't make a difference, but on the second flight when I added the electric fuel pump and waited about 3 seconds the reading went back to normal. This happens almost exclusively in climb. The engine does not change power or fuel flow. My mechanic thinks it may be a failing engine-driven fuel pump because it improves when I add the electric fuel pump but after reading these posts it may be the vapor issue mentioned by Diamond. Unfortunately, unlike most of you I have a 2003 with the VM 1000 engine monitor so no data downloads. I'm reluctant to change out the engine driven fuel pump on a 600 hour engine (Aviation Consumer says engine fuel pumps are supposed to last until TBO) but in an abundance of caution I probably will do so. Any suggestions regarding this particular set of facts would be welcome. Thanks.
Post Reply