Kavlico Fuel Pressure Sensor Failure

[Sportsman7064]

On a recent flight, as I rolled onto the runway and lined up, I flipped on my electric boost pump. Almost immediately, the Skyview system gave audio warning of "fuel pressure" which gets your attention. Looking down the value was bouncing around from 45-60+ psi (fuel injected IO-360 with Airflow Performance pump to a Bendix injection system). With the boost pump turned off, the value dropped back to the normal 33-35psi. After discussion with Airflow Performance, they suggested connecting a mechanical gage into the system near the sensor. Sure enough, the mechanical gage reads fine (33-35psi, then adds a few psi when the boost pump is on) while the Skyview reading was all over the place, much higher.

So I have a bad sensor, but this failure mode is confusing, since the sensor appears to operate normally without the boost pump...

Has anyone seen this sort of failure before. My attempts at a search did not work (pilot error, no doubt).

Thanks

Russ

 

[jakej]

A simple thing to do is slide off the purple silicone ‘seal’ from the 3 pin connector at the sensor, then try the test again - it may not fix the issue but is a simple/cheap option that’s worth a try.  The only other option I can suggest, given the tests already done, is to try another sensor.

 

[Sportsman7064]

I was slightly confused by your post (no reflection on you) until the replacement sensor arrived.  My original sensor bought about 2010, look like the one in the photo.  It has provisions for only one wire to attach on the terminal, and the instructions say to simply run a ground wire under the Adel clamp to ground the body of the sensor. 

The new sensor is about 1/2 the size of the old one and has 3 wires.  So apparently I had a VDO-style sensor...

Russ

 

[jakej]

Sorry, your subject heading was for Kavlico Feul Pressure Sensor Failure so I gave input based on that - the symptoms you have/had are typical of the VDO (that’s the one in the photo) units & that’s one of the reasons why Dynon don’t sell the VDO ones anymore.
That picture - hopefully the plastic line setup was being used for ground testing only ?   which Glasair model do you have ?
Ps - I’d also mount the unit up higher above the system connection point.

 

[Sportsman7064]

Sorry for the misleading title. I thought it was a Kavlico model...

Yes the plastic line was simply for a ground test run to see if a mechanical gage would read "normal" pressures while the sender gave the high readings. Just wanted to eliminate the pressure relief valve in the boost pump as a possible culprit.

The plane is a Glasair Sportsman 2+2 built in my basement using my exclusive 402 Weeks To Taxi program!

 

[jakej]

All good  . Just buy the correct Kavlico unit, you can use the same sensor wire however if you have the MAP sensor on the engine side of firewall then I’d splice into the 5 volt (red& white) & ground wires for the others needed ie you’ll have 3 wires going to the new Kavlico sensor.  Don’t forget to change the sensor type etc in the EMS menu 

 

[Sportsman7064]

All set.  My MP sensor is on the other side of the engine, but the red/white 5v wire for that sensor comes through the firewall above the fuel pressure sensor, so it was just a matter of splicing into the line and adding a length of red/white wire.  Updating the sensor type was easy as well.  I love the rather easy interface that Dynon has created.

Engine run on the ground completed over the weekend and everything works perfectly!

Thanks for the help.

I wonder if my VDO style oil pressure gage might be next to fail.  That one will get my attention even more!!

Russ

 

[jakej]

Oil press sensor - It could fail but they don’t seem to have the same failure rate as the VDO fuel pressure ones from my experience, I’ve never had to replace one. If it bothers you then I’d replace it to using the same wiring method etc.