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Garmin Fuel Pressure Sender Unit Rupture

Aussieflyer

Active Member
I fitted Garmin G3X (dual) & GTN650. I used Garmin engine instruments. The Garmin Fuel Pressure Sender Unit (Part Number 494-30004-02) failed after 6 months operation (80 hours). The sender unit ruptured fuel through the sender into the wiring plugs and pins and down the fire wall. Fire Hazard - possibly.

I have never heard of a sender unit rupturing before, however my concerns being if the factory could build one bad sender, there may be a batch of them out there.

Bought my gear in 2014/15. Not happy with Garmin as they provided no warranty. The unit new in the aircraft, however the warranty allegedly expired while sitting on my shelf, what happens when it sits on Garmin's shelves, apparently that's a different matter.
 
Hi @aussieflyer - did you ever get to the bottom of this issue. I'm going through the same problem. One sensor ruptured after 25 hours - I replaced it, now another ones just gone 20 hours later.
 
Failed Fuel Pressure Sensor

Hi @aussieflyer - did you ever get to the bottom of this issue. I'm going through the same problem. One sensor ruptured after 25 hours - I replaced it, now another ones just gone 20 hours later.

Good Afternoon,

We would be happy to look into this for you. Can you provide us with a little more information on your installation so we can help get to the bottom of this? What part number fuel pressure sensor are you using?

Thanks,

Justin
 
In response to your query. I replaced the sender unit in 2017 @ 80 hours. I'm now at 400 hrs and no problems with the replacement. I'm saddened to hear another unit has ruptured. I suspect more than just two units have faulted, I hope I'm wrong. Anyone else had a failure?
 
Hi Justin,
RV10 with dual garmin G3x and GTN750. 11-09477 GarminG3x Fuel Press Unjected 50 PSIG 1/8-27 NPT.
I've had 2 sensors rupture now each after 20 odd hours, exactly the same scenario as Aussieflyer - fuel through the sender into the wiring plugs and pins and down the fire wall.
I'll be stripping it this weekend and will send photo's.
 
Thanks @aussieflyer - good to hear your issue is sorted out and clearly the sender unit being the problem. In my case having burst 2 sensors now, I'm questioning the pressure output of my primer and fuel pump. I'll test these with external pressure gauge and revert back. This said I've never noticed and excessive fuel pressure reading whilst it's been working.
 
Justin, I would think that the senders would be rated to 100 psi at least. With Some electronic injections running near 50psi, I personally think that 100 psi of more is necessary.
Now we dont know that the OPs package is, but gee---this is a cause for pause:
So much attention to hoses to take large amounts of pressure and fluids, and a sender could rupture (using the OPs words) in flight is alarming.

Definitely need more information on this!
Tom
 
Sensor Specifications

Justin, I would think that the senders would be rated to 100 psi at least. With Some electronic injections running near 50psi, I personally think that 100 psi of more is necessary.
Now we dont know that the OPs package is, but gee---this is a cause for pause:
So much attention to hoses to take large amounts of pressure and fluids, and a sender could rupture (using the OPs words) in flight is alarming.

Definitely need more information on this!
Tom

Tom,

The proof pressure of this sensor is 2X and the burst pressure is 3X, which for the 50 psi sensor would be 150 psi.

Thanks,

Justin
 
Fuel Pressure Sensor RMA

Hi Justin,
RV10 with dual garmin G3x and GTN750. 11-09477 GarminG3x Fuel Press Unjected 50 PSIG 1/8-27 NPT.
I've had 2 sensors rupture now each after 20 odd hours, exactly the same scenario as Aussieflyer - fuel through the sender into the wiring plugs and pins and down the fire wall.
I'll be stripping it this weekend and will send photo's.

We would like to exchange the sensor for you and bring it in so we can characterize the failure and run some tests on the sensor. Can you email us at [email protected], so we can set up the exchange? Any pictures you have of the sensor installed in the aircraft would be helpful as well.

Thanks,

Justin
 
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Herewith Photos of the ruptured sensor, also showing the cross on the fuel pressure reading. Can see fuel leakage and how fuel has pushed the wire holding grommet out.
 
They're not branded Kavlico - which is possibly the problem, inferior alternates!?

Notice the Kavlico part number stamped in the sensor (P4055-50G). These are robust sensors; they're used by OEM's directly attached to diesel engines as oil pressure sensors where they live in a harsher environment than yours on the firewall, so this one must been part of a bad batch. GM uses these by the millions as oil pressure sensors, my 2003 Silverado included.

8xgRCBorzEIhMMJ8J4uQVhqzvfBSgNkGi56RnIEaOwBaYLLVOct36QM2aG9s4FXOK9mYgMXTpQgoFV1yxBOxOXiO2i5Vr0jdRrjZBI3gpHcGWYpMHjPUpt49cQ7d7hT-ZY-2E9VPOrBaZrYBZtq6rJEtiVqycrdPUnbXmcCwy3A9q4OHjz1nYvIdtB5WEEJfaU-tDPDzxWjGI-uRATzun83_QxeRWTuvF17Y2PmG50_fCjps7741qRky72yMnDzAN4LUhAyKrrDG1skLqmCv2fdSWNxYfN8GeSh5IKygM6AYD_KWdPOb_40A2LLuVE46rLZN7QhicBpBsQBOFR7-cahYrFSYQgYXTmQ5NNyJYmPmajcXYFoRXWPPtDYX6yBhFv1ZaLCXV0pShlK_U8KAOyIrs5T7gaozXRFxflstB843YGODCARvsn9brkAb_1SsJK6se55_ZrzzsVkLX6Nlr1vg7xzxwmWXAkk-zW-ccG8N2Nk6nM8_20fOHEqgCz3JLTUKcguoYTMFE9BAsc5ku-c52Oj7T-ftQHL9yg75F8-_jRIODA5I1MHWDisdQ4JjqK9Yyc-QmMugbvcMpUuXNklUcrfSLofxyA1hgYgBeZPlpBhbSqEgZuIl8ZYCXnZg-uqo79vN37JPvY5HTT1AN8sCnAZtoXmSdlQUqZaK8pLp7bixQbvYz37Lkb_70VbPv-RdL3hNrVzBRcYL6ERnrEuk8AVoDh51zS0ryE4MoKAhcUWuJxs5=w480-h640-no
 
I would suggest installing an orifice in the line to the sensor if possible. It is standard practice to put one in the oil pressure line, looks like a good idea for fuel.

I believe most use a #60 drill for oil. Due to the viscosity of fuel, smaller would be better. I have drills down to #90 which are very interesting to use. Best way is to do the 470 rivet in an AN fitting trick and drill the hole in a lathe. It takes a special chuck to hold the drill this size. Free-handing a #90 requires several extra drills!
 
Fuel Pressure Sensor

Thanks for confirming. Hope it is a bad batch and not an issue with my fuel booster pump.

Good Afternoon,

It is a little difficult to tell from the photo's, is there a sufficient amount of strain relief for the wires coming out of the sensor? Depending on where the wiring bundle it is connected to is terminated, this could be causing undue vibration/stress on the unit, during normal operation or engine start/shutdown. We would like to take a look at your sensor whenever you are able to swap it out with your Garmin Dealer.

Thanks,

Justin
 
Fuel Pressure Sensor (Injected), 50 PSIG, 1/8-27 NPT

I have just learned from a Garmin Dealer in Europe that Garmin has discontinued the 494-30004-02 Fuel Pressure Sensor (Injected), 50 PSIG, 1/8-27 NPT.

Is this because of a quality issue or other reasons? What would be a reliable substitute to feed the G3X?
 
Hey Justin----if the senders have a 2x rated working pressure, then I'm wondering why this would be an internal failure. 60 psi isnt a lot in the grand scheme of things, but enough to cause a major melt down.
Has Garmin done any additional tests to see what the problem is?

Just asking-
Tom
 
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