Matt's RV-8 Project



Matt Dralle's RV-8 Project
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Date:  4-4-2010
Number of Hours:  2.00
Manual Reference:  
Brief Description:  Calibrating Princeton Capacitive Probes - Part 2

I let the ProSeal cure for three or four days and then took four 5-gallon cans over to the airport fuel island and put $94 worth of Av-Gas into the containers (that's just enough fuel for ONE of the TWO fuel tanks, btw...) I actually put exactly 5.25 gallons into each container as this is the total amount of fuel per tank divided by 4 - one container per set point.

On the left tank, I went though the calibration steps adding one container of fuel per sent point until I had a tippy-top filled tank. But then I noticed that the EIS-4000 was only reading 16 gallons using the recommended calibration factor of 105 (21 gallons / 2 = 10.5 * 10 = 105). I measured the output voltage from the probe and read something like 3.6v instead of 5v. I then measured the supply voltage and found I was only getting 9.3v instead of 12v! I had used the "flow transducer supply 12v" output on the EIS-4000 to supply power to the fuel probes and I guess there wasn't enough current to run them, thus the voltage drop.

I emailed Todd at Princeton and he said that the probes would need at least around 9v to read correctly, so I pulled the EIS-4000 out and cut into the wiring harness and rewired the fuel probe supply lines to the +12v supply feeding the EIS-4000 itself which is a switched circuit off the VP-200. Now I was getting a solid 12.5v at the probes.

I drained 21 gallons of fuel out of the tank through the little valve in the bottom of the tank which took about an hour, paying attention to when each of the respective 5-gallon containers was full and quickly swapping them so as to not spill fuel all over the carpet!

Cont Next Log...
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Fuel Probe Lights

Fuel Probe Lights

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Fuel Probe Lights

Fuel Probe Lights

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Fuel Probe Lights

Fuel Probe Lights

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