Anyone have a 72' or 73' FSM handy??

[cruiseroutfit]

If so, can you check and see if it has any notes regarding the fuel guage as per this:
IH8MUD.com Forum - View Single Post - Fuel and Temp Gauges

Thanks in advance

Free Cruiser Outfitters t-shirt or hat to the first person that can tell me what the "switch" does

 

[dfmorse]

Kurt;

Here is what I've got on this so far.

My older manuals don't have the detail required to shoot this out properly. Besides, the schematics are a night mare.

However; manual 98154 gives some clues to the way this water gauge and fuel gauge are coupled inside the combination meter.

Page 12-26 show the interconnect of the two gauges, but not the internal switch u have found. There is a voltage regulator common to both gauges (2-7 volts); i.e., these two gauges want to see 2 to 7 volts (not 12 volt battery). Perhaps the third terminal is for this purpose. For example, when u turn the ignition "on", 12v is applied to the voltage regulator (inside the fuel gauge); as the fuel gauge coil begins to activate, it trips the 'switch' applying 2-7 volts to the "water temp gauge".
This may be used (the switch) as a de-load system. In other words, get the fuel gauge moving first, then kick in the temp gauge. When it kicks in is determined by the set screw.



Or, the third terminal was used as a calibration point for factory use.

...

 

[kvanoort]

Not sure if this is helpful:

http://www.globalsoftware-inc.com/coolerman/fj40/schematics.htm

 

[Pin_Head]

The schematics I have seen indicate that all of the gauges (except amp meter) are wired so they get power from the same fuse in parallel, then they run to a sending unit that is grounded. As the resistance drops in the sender, the gauge reads more to the right as more current flows through the meter. Just looking at the picture, it looks like the screw might be used to adjust the meter sensitivity for the full or empty position. Another possibility is that it might be there to work as a dircuit breaker to limit damage to the meter in dead short conditions.

 

[cruiseroutfit]

The schematics I have seen indicate that all of the gauges (except amp meter) are wired so they get power from the same fuse in parallel, then they run to a sending unit that is grounded. As the resistance drops in the sender, the gauge reads more to the right as more current flows through the meter. Just looking at the picture, it looks like the screw might be used to adjust the meter sensitivity for the full or empty position. Another possibility is that it might be there to work as a dircuit breaker to limit damage to the meter in dead short conditions.

Ditto, every single FSM and schematic I could dig up, shows a full 12V to each guage. But I am now 100 confident this is OEM. The "switch" might act as a circuit breaker (I'm going to rig it up and test it today), but why just on the fuel and temp guage and not the oil pressure too?

The screw doesn't seem to adjust the meter sensitivity, rather set an on/off position for the contact points. Unless the bimetal switch (with the heating coil) acts as a resistor (need to test), the top-middle post is going to get 12V+ so its not acting as a voltage regulator in the sense of knocking down the votage.

 

[brew8]

I looked at one I have it has a coil around the long part of the contacts, could be around a bi metal strip to open it on high current, which for this couldn't be much, Larry