Fuel Shutoff Solenoid - how's it work?

   / Fuel Shutoff Solenoid - how's it work? #1  

Jay4200

Veteran Member
Joined
Nov 23, 2005
Messages
2,028
Location
Hudson/Weare, NH
Tractor
L4200GST w/ LA680 & BX2200D w/ LA211
The fuel shutoff solenoid on my L4200GST has never worked since I bought it (at ~2000+ hours) - It runs like a swiss watch, but I have to pull the kill knob to shut off the machine. I actually never knew that the tractor was supposed to turn off with the key, but once I found out, figured I'd fix it someday. Today is that day (figuratively speaking).

The solenoid plunger is out, so there is no effect. I have to assume that it pulls in when it is activated, but can't figure out how that is supposed to work from an electrical standpoint.

If the key is off, I have to assume that that there is no power at the solenoid, so shouldn't the plunger be out? If the plunger is out when the machine is off, how does it shut down the fuel? OR, does it pull only in when the key is off but the motor is still running?

If I put a voltmeter on the wire coming into the solenoid, what should I be reading for: off, running, running w/ key off.

Thanks much - JayC
 
   / Fuel Shutoff Solenoid - how's it work? #2  
Hello Jay…
The solenoid gets just a short, one or two second, pulse of 12 volts from the kill relay located under your dash. This relay, (Timer Key Stop), is on the extreme right toward the front. There are Three “relay looking” boxes mounted on a metal bracket under the dash.
The “relay looking” one on the inboard side is the Glow plug relay, the one to the rear of the outboard side is the glow plug controller, and the outboard front relay is the Timer Key Stop.
I suspect you may have a bad connection at the plug in on this relay, or the relay itself is bad… KennyV.
 
   / Fuel Shutoff Solenoid - how's it work? #3  
JayC:

It has been several years since I had the same problem, but here is what I think I remember. The resting state of the cut off solenoid is with the plunger out. The plunger presses a spring loaded lever that opens the fuel passages. When the key is switched off, a timer retracts the plunger for a few seconds and, since fuel is then shut off, the engine dies.

So, if you take the solenoid off so you can see the plunger (as you apparently have done), and ground the solenoid case, the plunger should retract for a few seconds when you turn the switch off.

So a voltmeter on the solenoid terminal should read 0V unless the key has just been turned off, when it should read 12V for a few seconds. As you probably know, if you get those readings and the plunger doesn't retract, the solenoid is probably bad ($70 if I remember). If you don't get those readings then it must be the timer, relay, or switch.
 
   / Fuel Shutoff Solenoid - how's it work?
  • Thread Starter
#4  
Thanks doods! I figured you'd pop up with this post Kenny ;). Momentary relay, eh? I'll have to look for that (unless I actually read 12V at the solenoid, of course). I seem to remember that there is a fuse that is many times the culprit. I'll be sure to look for that first if I'm not getting any voltage.

Thanks again - JayC
 
 
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