I need help understanding the fuel system

[duanelr]

My bike is an FJ1200 '87.

What is the purpose of the wires leading from the fuel petcock? I.e, sensor, solenoid, switch?
Frankly I'm lost in understanding the make up of the fuel-system before the carburetors.
Thank you, Duane

[FJ_Hooligan]

Those 2 wires activate a solenoid which shuts off the flow of fuel when the tank gets low.  When you feel the bike start to stumble because it's running out of fuel you toggle the RESERVE switch which will shut off the solenoid and restore the flow of fuel to the carbs.

Next, find the nearest gas station.

[duanelr]

Thank you for the reply!
When everything is dead silent, the key is on, and my ear is pressed against the that part of the tank, should I be able to hear a solenoid click?
(I'm not sure mine is working) or maybe a better way of saying this, is there a better way to test it?
Duane

[red]

Duane,

The safety wire around the fuel valve is to hold the gas outlet fixture in place.  It is only held by a grommet, with some sealant.  With age, the fixture can come loose, causing a gas fire and loss of the bike, and maybe more.  A wrap of safety wire, holding the outlet in place, makes the valve assembly much safer.
.

[FJ_Hooligan]

The solenoid is only "on" when the fuel level is low enough to activate it.

Empty the tank then listen or better yet check for voltage

[Pat Conlon]

....better yet, throw that petcock away.
Get a less expensive '84/85 petcock that has a prime function. It's plug and play.
Why? If you are on a tour in the middle of BFE and your vacuum petcock loses it's diaphragm seal and the fuel shuts off, the prime function on the 84/85 petcocks will get you home. (ask me how I know)
If the same thing happens with the '86/87 petcocks that have no prime function, I hope you have cell coverage because if not, you are going to be walking.
The Reserve functions suck.
They are unnecessary when your bike has a fuel gauge, fuel level warning light and odometer.
Keep the oem rocker switch and use it for something really useful like driving lights or ____________(fill in the blank)

Just get caught out, passing a group of cars and have your bike start sputtering on you, oh yea, that's really really fun. (ask me how I know)
Stupid fucking reserve....

Ok, I feel better now....

[Sparky84]

(ask me how I know)
Ok, I feel better now....

and How do you Know Pat?   

[Pat Conlon]

 

[andyoutandabout]

Well I certainly know all of this as of August 2019 and the off ramp at Benbow on the 101. Diagnosis petcock had me limping to Oregon and the house of Frank, where a new manual model, lock wired and ready to go, was posted by our friends at RPM.
Phew.
Trip saved.