Sender, Fuel (P/N 95-3971); Solenoid - Toro 315-8 User Manual

GLOSSARY
Sender, Fuel
(P/N 95-3971)
Figure 19
Purpose
This electrical component monitors the level of fuel in
the tank (Figure 19).
How it Works
A float is attached to a pivoting lever. This lever rotates
a potentiometer (a device much like the volume control
on your stereo) to vary resistance. The resistance will
be 25 to 200 ohms, plus or minus 20%.
Testing
1. Before removing the unit, verify that the float has
not sunk. Replace the float if it is sunk.
2. Disconnect the sender unit from the wiring
harness and remove from the gas tank.
3. Verify that it matches the resistance in the
following table.
Float Position Resistance
Full 25 ohms +/- 20%
Empty 200 ohms +/- 20%
3 - 16

Solenoid

Purpose
The solenoid's purpose is simply to connect the battery
to the starter motor when the ignition switch is turned to
"START". The solenoid is used to protect the ignition
switch from the high current drawn by the starter motor.
How it Works
The solenoid has two primary parts. One is a coil of
wire wrapped around an iron core. Whenever 12 volts
is applied to the coil, it becomes a magnet. The other
part is a bar type switch (Figure 20). Because it has a
large contact area with the contact terminals it can
easily handle the high current loads required by the
starter motor.
mvc-118
When 12 volts is applied to the coil, it becomes an
electromagnet. This quickly pulls the bar toward
contacts and closes the switch. When power is
removed from the coil, the spring loaded bar returns to
its "normally open" position. The solenoid closes and
opens the switch very quickly. This minimizes the
"arcing" that can damage other types of switches.
The ignition switch is protected because only a small
amount of current is needed to activate the coil.
Figure 20
XL Solenoid
Demystification Glossary