Centroid sender reset

[cgoodwin]

Thanks to Frenchfry!

1. 9/15/09: SUMMARY FOR MY RECORDS
Mike has a cgfp-8.9-12v-240/33-lo-dsl-5h sender dated 7/09, presumably from Frybrid, meaning the fuel is vegetable oil. It initially read E at empty and F at full and was moving downscale with use, but then started going back to F. He has not attempted to recalibrate but does have a magnet from Radio Shack. The reading can go from E to F in about 1-2 seconds. The tank has baffles and is long and narrow. The gauge is Autometer.

9/22/09: MIKE REPORTS:
--Mike road from 3/4 tank to E and got a constant E reading, other than the initial POP each time he turned on the ignition.

2. CALS
Given that the POP (power-on peg) is working correctly, the false Empty seems almost certain to be calibrations, though you havent changed the calibrations.

You wont need a magnet. The cals are done by shorting Send/Neg at powerup. Try following this procedure and let me know what your readings are after that:

EMPTY:

--Have the sender out of the tank to simulate empty. If you can drain the tank without removing the sender, and that's easier, that's fine too.
--Have the power off
--Put the black lead of your voltmeter on the sender's NEG terminal and use
the voltmeter red lead to measure the other terminals. If a reading is
*negative*, show a minus sign with it:

Pos/Neg=___________vdc (expected: 0.0vdc with power off)

Send/Neg=___________vdc (expected: 0.0vdc with power off. So if you've
got your gauge powered by some other source and dont turn off that power, it
will confuse the operation).

--Put a jumper between Send and Neg. A clip lead is ideal because you can
take it off easily. But first measure the resistance of your jumper
__________ohms (expected: less than 1 ohm), because alligator clips can be
broken inside their jackets without that being obvious.

--Have your voltmeter hooked up so you can watch the Send/Neg voltage while
you do the cal.

--Have someone turn ON the power for you and count "1000-1, 1000-2" (ie 2
seconds), at which point you remove the jumper. The voltage should have
been 0 volts with the jumper on ___________ and then it should do some
bouncing between a high voltage and a low voltage before finishing on the
Empty voltage, which for a 2-terminal sender would typically be around 8
volts _______________

FULL:

--Turn OFF the power.

--Put the sender in a full tank of the appropriate fuel (not water). [NOTE: you dont have to do this right away if you dont want. Each time you fill up, the Full Detection circuit will notice and tweak the Full cal if needed. Before the first fillup, the reading will be only approximately right]

--Turn ON the power. When you set the Empty, that enabled the Full
Detection function. There's a stinger at the top of the sender that watches
for fuel up near the top of the sender. When this is wet, the sender sets
its own Full, so you should get a Full reading at this point
_______________.

--What is the Send/Neg voltage?___________ (typically maybe 3.5v for 240/33 ohms)

Joel