Stewart Warner fuel senders

[n86121]

It's about that decade again, time again to cleanup the fuel senders!

Every few years the outboard senders (mostly) seem to need some love. Perhaps it's because on occasion the tanks are not left full and the outboard elements are left exposed to some air in the tank?

Anyway

SUPPLIES

A. Tarn-X or other metal tarnish /polish / remover
B. Contact cleaner
C. Q tips

STEPS

1. Being really careful to NOT drop anything into the tank, remove the senders.

2. Note the small o rings around each screw. Save or it will drool around the holes.

3. Use tarn-X with Q tip to clean tarnish off wirewound resistor inside each sender

4, Extra points
Measure their swing with meter. Should get mostly smooth change over range.
The little tabs can be GENTLY bent to adjust limits, especially so sender does'nt go off the end of the wirewound resistor at either limit.

NOTES:

The main senders are wired in parallel to ground.

From measurements I took and noted 25 years ago, noted here so I can lookup again when I'm 75 yrs old, IF I remember this website!

Location/TANK FULL EMPTY Part Num Circuit resistance to meter

Outbrd MAIN sender
Full 118 ohms
Empty 10 ohms
part no 14260-12

Both MAIN full = 28 ohms
Outboard tank empty = 7 ohms
Inbrd MAIN sender
Full 28 ohms
Empty 0
Part no 14260-11

Both mains Empty = 0 ohms

===

AUX
Full 28 ohms
Empty 0 ohms
Part no 14260-13

LockHaven Air Parts will overhaul for about $140 each, provided wirewound not broken.

Oddly enough, the resistance is highest when full, and goes down with quantity, so an open (failed) circuit shows FULL
Sensors are in parallel to ground, closure to ground shows empty - which is only condition required by cert.

Also note, tanks empties faster as tanks get lower (using inboard sensor)

Enjoy!