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Thread: New style Kavlico sensor for fuel pressure

  1. #1

    New style Kavlico sensor for fuel pressure

    I installed the new style Kavlico oil and fuel pressure sensors. The oil pressure reads fine but the fuel pressure shows 38 PSI. I changed the values on the 5500 touchscreen by SET-CAL-ADMIN-ADMINISTRATOR MODE then back to Instrument Calibration-Fuel Press as per Jonathan’s suggestions.

    ADVAL SHOWED 1514 initially then 810 later.

    Here’s what I inputted:

    DISPLAY(PSI) ADVAL
    0.0 500
    100.0 3167


    The User setting #11 shows part number 41,150 KAV 0-150

    Any idea how to fix this, anyone know what I did wrong? Perhaps I have the wrong sensor selected. I have V16 software update.
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    Last edited by Oly148; 12-05-2021 at 04:00 PM.

  2. #2
    Oly,
    This is the correct calibration for the 150PSI Kavlico V2 sensor, which is what we sold you for fuel and oil. When are you registering 38 PSI? In flight? After shutdown? If it's after shutdown, this could just be trapped pressure in your system, crack the line or open the throttle and mixture to allow the pressure to bleed out, see if the PSI drops to zero.

    If you want to test whether the sensor itself is bad, this is why we moved from a 50PSI sensor for fuel to a 150PSI sensor, beacuse now it is very easy to test just by swapping your oil and fuel PSI sensors with each other. If your oil PSI still reads as you'd expect after swapping, then it isn't the sensor and it will be time to start exploring whether this high fuel pressure reading is, in fact, legitimate.

  3. #3
    Jonathan,

    This was the first engine start after receiving the engine back from overhaul by Aerosport Power. I have not flown it since overhaul yet for this and several other issues I need to address. This was the reading while the engine was running. Before engine start the fuel pressure read zero. Normal start procedure is to run fuel boost pump until fuel pressure starts reading then shut off boost pump and start. After engine start the fuel pressure slowly crept up to 38 PSI and stayed there until after engine shutdown. All other indications like oil press, cht, & egt readings appeared normal. I should have reported that during the very first start the #2 fuel line from the spider to the injector nozzle was spraying fuel out of an undetectable crack underneath one of the adel clamps. I replaced the fuel line and the engine ran fine except for the high fuel pressure. Perhaps this introduced too much pressure in the line but by removing the existing line and replacing it but I would think this would expel any excess pressure in the line. I will check with an A&P and see if we can track this down. Just wanted to check with you first and make sure it wasn’t a configuration issue. BTW- after replacing the fuel line there were no fuel leaks of any kind.

  4. #4
    Finally solved the issue. The configuration change that Jonathan recommended had no effect on the pressure reading. I did connect the Kavlico fuel pressure sensor to my air compressor and verified that the indications are rising and falling but still reading about 12 psi too high for both pressure sensors (fuel & oil). I finally put in a call to Rob Hickman and he fixed the issue in minutes. Evidently there are two jumpers on the back of the engine board that need to be cut (or rather scratched off). The engine board was set up to use the older style analog VDO sensors and this modification to the engine board is necessary for the pressure indications to be accurate for the newer style digital sensors. The configuration changes Jonathan recommended still need to be made but the other issue was this engine board modification. BOTH need to be done for accurate measurements to the EFIS. See below, if the resolution isn’t good enough contact AFS for the originals or send me a PM and I’ll forward my images.

    By the way- it looks scary at first but it’s rather easy to modify the engine board, even an Avionics/electrical neophyte caveman like me figured it out.

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    Last edited by Oly148; 12-30-2021 at 08:56 AM.

  5. #5
    I have the opposite issue - my 5600 is reporting a fuel pressure of about 5 PSI. I'm told that it should be significantly higher. I've just completed a fuel flow test so I believe the fuel pump is okay. I swapped the Kavlico 150 PSI V2 sensors (oil and fuel) and the reading didn't change much. I haven't started the engine yet so I don't know about oil pressure readings. Could this also be a jumper issue?

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