Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 25781
Location: Livermore CA USA
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 Posted: Tue Apr 06, 2010 8:06 am Post subject: (UPDATE) Princeton 18-5B-5S Fuel Senders Won't Calibrate... |
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Dear Listers,
I was able to get fairly good access to the fuel sender from under the airplane and so I removed the 5 screws with a right-angle electric screwdriver attachment and gently pulled the sender about 1" out. As I did this, I noticed that the tip of the probe seemed to touching the bottom of the fuel tank. Recall that the probe comes prebent in a "U" shape for RV installations. I thought that perhaps the tip of the probe touching the tank wasn't a good idea, so I gently twisted the fuel sender so as to slightly bend the tip of the probe up just a little bit. I pushed the sending back into the hole and put two screws in to hold it in normal position. I applied power and pressed the button down to get it into calibration mode. I got the one flashing LED indicating Empty set point as before. I pressed the button once again to get the 1/4 set point, and much to my surprise, I received to next sequence of two flashing lights!! So I tried the same procedure on the left tank and got the same results! Yahoo!
When I pulled the sender from the tank, the Proseal 100% stuck to the metal tank and released from the sender. This worked out really well as it formed a nice gasket. I mixed up a batch of Proseal and applied it to the probe and then used new screws and reassembled both sides. After the reinstallation, I tested the power-on/first set point again and was pleased to see that it was still working! Yahoo!
So, after the Proseal cures, I'll try the calibration with fuel again. Hopefully it will go through all 5 steps and I can just move on with this!
I was all ready to replace the Princeton's with the standard S&W floats, but when I got to looking I realized that I had powered the Princeton's with +12v, and the floats require a 470 ohm to 4.8V. So, changing to the floats would require rewiring behind the panel and that's a whole lot of work I'm just not up for right now!! Hopefully the Princeton's will calibrate fully now and I'll be back on track!
I'll post another update after my calibration escapade...
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
At 05:37 PM 4/4/2010 Sunday, Matt Dralle wrote:
| Quote: | Dear Listers,
I installed Princeton 18-5B-5S Fuel Senders in the left and right fuel tanks with Proseal (see attached). Last week I installed the wings permanently and today I torqued all of the fuel lines from the wings to the fuselage. I got 21 gallons in 5.25 gallon increments ready to calibrate the 5-set point Princeton probes today. They both powered up fine and started flashing the left light indicating the Empty set point. I pushed the button once per the calibration instructions to go to the 1/4 level. Instead of getting the #2 led flashing, I get the all three LEDs flashing sequence indicating that probe "Can't be calibrated"!!!
From the installation manual: CAL Error (three flashing LEDs) - The probe failed to calibrate. Possible causes: water in the tank (NO), inner brass rod is shorted to the outside aluminum tube (PROBABLY), Alcohol in the fuel (NO), trying to calibrate full first instead of empty (NO), or the probe electronics have failed (MAYBE)." Yeah, you read all that right.
The best part of this story is that I Prosealed these babies in, installed the wings, and now discover that both probes are defective or what even. How can this fricken be? Its too late in the game for this. Replacing these stupid probes is going to be a major pain not to mention the fact that likelihood of leaks are now going to be high. I just can't believe it. This is so frustrating. Why didn't the manual advise to check this long before now? Like before they were installed, during installation, and right after installation before the Proseal cured?
Oh, did I mention BOTH are bad? How can this be... How disheartening. Please tell me I'm just mis-reading the calibration instructions...?
I'm going to go out on a limb here and say avoid these piles of garbage...
Matt Dralle
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