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Thinking more about your issue: If you are using the JPI and Piper gage on the same sender I would disconnect the Piper gage and see what happens on the JPI system an likewise the use Piper gage only.
The Piper fuel gage system is current driven. The gage is basically a Wheatstone bridge that measures current. The sender changes the current flowing thru one leg. The gage is an amp meter calibrated in gallons. I don’t know what the JPI uses but being solid state I suspect it is looking for voltage signal.
I think the JPI and Piper system are not playing well together.
JPI does not use voltage, its current driven as well and you use the resistance readings to "calibrate" the gauge as you fill the tanks. I will drain the tanks and go through the calibration again after I verify the gauges separately.
I think the best bet for me is to one day in the near future install the 25 gallon tanks with sight gauges and not worry about the electronic readings other than fuel flow and total burned.
thank you both i will do some more trouble shooting and get back with you. i have found some good trouble shooting info on this sight and will be verifying the unit is bad. it was replaced with a new one about 15 years ago so i will use this info to check and verify its the sender. Terry
thank you both i will do some more trouble shooting and get back with you. i have found some good trouble shooting info on this sight and will be verifying the unit is bad. it was replaced with a new one about 15 years ago so i will use this info to check and verify its the sender. Terry
Check the ground wire... double check the ground wire. Clean it up, then run a new ground wire and double check new ground wire. Are you seeing a pattern here for bad readings?
Check the ground wire... double check the ground wire. Clean it up, then run a new ground wire and double check new ground wire. Are you seeing a pattern here for bad readings?
Great advice.
I ran a new ground wire from the tank sender to the avionics central ground. The original ground to the wing is NOT reliable.
When I was checking mine out, I found it relatively easy to check resistance in the sender rheostat. If it goes from zero to about 30 ohms -- highest resistance when float is UP -- the sender's good.
Ditto what Gilbert said -- both my tanks already had a second ground wire, from the sender to the frame. (In my case, I had then both wired back asswards... noobie mistake!)
Does anyone have a source for the 30 Ohm wire wound resistor at the back of the piper fuel gage? The insulating phenolic on one of mine has broken off.