Farm Trac 390 HST Fuel shut off solenoid not working

[bcribb]

I am having trouble getting my fuel shut off solenoid to work on my 390 HST Farm Trac tractor. I have bench tested the solenoid and it pull in. It seems to be working fine till I hook it up on my tractor. It has 3 wires , white, red and black. I know the white wire is pull in or start. The red wire is hold and the black wire is ground. I can't find the source for where these wires are coming from except for the ground. I have a new start relay but can't find the old one to replace it. Maybe this tractor don't have a start relay. It seems like the power to the plug for the solenoid is intermittent. Sometimes I have power and sometimes I dont. Does one of these wires go straight to the ignition switch? I cant find a wiring diagram for the starting system and The manual I have has proven to be wrong on certain things like the placement of the injectors crush washer saying it goes on top of the fuel return rail. Found that out by the Pump Guy.. Any help on this would be greatly appreciated. Contact me by PM or email or by this forum.. Again thanks for any help..
I've attached a picture of the solenoid and some of the relays i've found under the dash.

 

[doneill127]

I have a Mahindra with a Mitsubishi motor and the solenoid looks very similar. On mine the solenoid pulls in when you turn the key to engage the starter, then de energizes and the hold circuit energizes when the key is released to the run position. Attached is a wiring schematic of it. The ETR is the shut off solenoid. Assume yours might be similar.

 

[atsah]

So your tractor won't shutdown when the key is turned off? Most I have seen have a relay between the key switch and the solenoid, it takes 5 to 8 seconds for the pin to retract after the tractor is shutdown. When you bench test it the relay time is taken out of that equation. After you removed the solenoid did you attempt to move the "rack" in and out to make sure is was moving smooth with no binding? My guess is the relay or the connection to it is suspect.. I haven't seen many relays fail to tell you the truth..

 

[bcribb]

I checked all the wiring to the solenoid today. Replaced the start relay after I finally found it. Did not look anything like the new relay. Worked fine for a few times of starting and shutting down then it wouldn't shut down. Made an adjustment on the solenoid and checked some more wiring and got it going again. I also put the old relay back in and it seemed to be working too. Mystery to me.. Thanks for the response..

 

[bcribb]

I found the relay finally and replaced it. Also checked some of the wiring. Seems to be doing ok at the moment. Thanks for the wiring schematic and your response.

 

[atsah]

That solenoid is sticking I believe. Sometimes they fill with oil and don’t work properly. When you say you made an adjustment to it what did you adjust? I can’t see how it can be adjusted.

 

[bcribb]

The solenoid was also not screwed in enough for the pin to hit the fuel shutoff lever. Adjusted that too and its working fine.

 

[atsah]

Got it, I see yours is threaded with an adjustable nut.

 

[bcribb]

That solenoid is sticking I believe. Sometimes they fill with oil and don稚 work properly. When you say you made an adjustment to it what did you adjust? I can稚 see how it can be adjusted.

By screwing the solenoid in or out it adjust how far the solenoid pin is from the fuel shut off lever inside the pump. It has a nut to lock it in place after the adjustment. If the solenoid is screwed in too far the tractor won't crank because the pin is still to close to the fuel shut off lever. Maybe there's another adjustment i'm missing and don't know about it. I do know the way i'm doing it its very sensitive. The solenoid is only screwed in by a few threads. Also with the solenoid out the tractor fires right up. With it in it has to turn over a lot before it will crank. I hope i'm missing something and you can shed some light on the proper way to make an adjustment.

 

[atsah]

Seems to me you would have to measure the distance from the pin on the solenoid to the were it touches the injection pump rack and set the lock nut at that point for it work like it should. Do you have a picture of were you mount the solenoid on your tractor? With your solenoid setup being threaded in with a lock nut I would say it's a fine line were the solenoid works and were it doesn't work.