fuel shutoff switch on M977 HEMTT

[Karl kostman]

Hey guys I fired up my M977 HEMTT the other day and went to shut it off and the fuel cutoff switch next to the ignition switch did not cut the fuel off. Is this switch just a simple momentary switch that cuts the electricity off to the circuit that allows fuel to flow or is it something more complicated than that? I need to replace the switch and am wondering what I need?
Thanks for your thoughts on this guys!
Karl

 

[Guyfang]

Did you TEST the switch?

 

[Karl kostman]

I did not I take it out of the truck tomorrow and test it to insure that its bad. is this a 24 volt switch or a 12 volt?

 

[Guyfang]

Voltage is not important in testing. Will the contacts close when turned on. Will the contacts ope, when shut off. Thats important. But I would think its 24 volts.

 

[Karl kostman]

Guyfang I pulled the switch today and tested it and the contacts open when I activate the switch so the switch appears to be operating fine obviously that moves the problem down the line. On top of the engine is a canister looking item with wires attached to it and a lever on it, please correct me but is this the actual fuel shutoff device? If so I should put the switch back in and test that canister device to see if I am getting voltage there??

 

[Guyfang]

I don't know. Would have to see a picture of it. I am a generator guy. So asking me is dangerous. Let me see if I have a schematic. I am guessing here, but the switch probably opens and closes a relay, solenoid or something like that. But The last time I fooled with a M977, George H.W. Bush was in office.

 

[Karl kostman]

guyfang the fuel solenoid is electric I am going to go over there tomorrow with my wife and have he activate the shutdown switch and I will take some electrical reading on the connections on the solenoid. I will also make sure that its not froze up since the truck has been sitting for 3 years not being run. I have to pull the radiator and thats a fairly substantial job so I have been in no giant hurry to dive into it!!! I will let you know what I find tomorrow!

 

[Guyfang]

Normally if you hold the solenoid in your hand, and someone turns it on, you should feel it move. Or even sometimes hear it. If the solenoid has two wires, then you can also try hooking 24 VDC up to the wires, and testing it.