John Deere 790 stuck in the middle of the field, dead, won't stay running.

[Matt621]

Bought a used 2006 790 with 600 hours on it. It worked at first fine. But then I started having troubles. Initially it was the seat switch. So I fixed that. But today it just kept dying. I thought it was the seat switch again so I bypassed it. Okay, once I did that it would start. But the moment I put in gear (clutch in) it'd kill the engine. If I engage anything to the engine it would die. The I recall I had trouble with the parking brake. So I engaged it and disengaged it several times. Finally it started working. For about 30 feet. Then it died. Then it started again.... lifted the bucket, started to dump then it died again. And on and on and on. I finally just left it in the field and walked home. I'm sick of it.

If it'll start it'll idle and rev fine. It'll go to red line or sit idling as long as I ask it to. It only dies when putting it into gear or if it's in gear moving then it'll just die while moving and won't start again.... until it decides it will.

I'm covered in dirt and dust, going to take a shower. If anyone has any ideas on what is going on, please lmk. I can't find much online in the way of wiring or diags, it's all just simpleton stuff on how to verify things are working (same for the manual.)

I'm very mechanical, but totally unfamiliar with this JD stuff.

Thanks

 

[LouNY]

One way would to be remove the fuel shutoff solenoid, or figure the proper way to bypass all the safeties.

 

[Matt621]

If i knew were all the safety switches were and have a wiring diagram that's exactly what I'd be doing. But so far I can't find that information online.

 

[Wagtail]

G'day Mate and welcome to TBN from Downunder.

Not knowing where in the world you are, a suggestion is to visit your 'local' JD Dealership and ask their Parts Department for copies of the relevant wiring diagrams you require... they'll print them off for you at no charge. (I know that my dealership will and has done this for me) My dealership will also grab a mechanic out of the shop to discuss any fault I may have, again, no charge.

Enjoy the site.

 

[Matt621]

I'm out in the sticks. At least an hour away from anything like a JD dealship but Monday i'll call one and see what I can get. I'm just shocked it's not available online. There are a zillion people searching for John Deere safety switch but very little information and none on the version I have. I took apart the seat switch but it's not it. It's as soon as I engage the transmission or PTO.

 

[DieselBound]

When you engage the PTO you're not in gear? Any difference if depressing the brake (there may be a switch here for the safety circuit).

There's circuit logic. Might be that some sensor/switch that is expected to be disengaged/engaged isn't in the proper state.

I'm thinking that Lou probably has the right call, that it's the fuel shutoff solenoid. I think that you could watch to see what's happening (mechanical action): could also put a meter on it and see what it's doing).

Have to wonder how many injuries there have been trying to diagnose issues like this? "Safety" stuff causing accidents!

 

[Matt621]

The problem is actually two fold.

#1. just to get it started is a hit or miss. Right now it won't even start regardless of anything I do... then randomly it'll just start like nothing was ever wrong. So that's part one.

#2. Once I do get it started it runs great. Until I try to engage anything. Any gear or the PTO. Anything that would normally transfer power to something. The hydraulics work fine. (bucket).

 

[Matt621]

Anyone have a list and location of all the safety switches on this thing?

 

[DieselBound]

Hit and miss always has some pattern. Until you get a schematic I'd suggest doing a lot of detailed troubleshooting via manipulation of various actions (thermal cycles; ignition switch jiggling, moving levers etc.).

If the hydraulics work then it's not load-related (and unlikely fueling issue). It would seem to be safety-related as gear and PTO operation are generally things that are in safety-circuitry.

My Kubota B7800 has a really hit and miss start operation that is related to its clutch engaging a safety switch (the switch is in an impossible location, so I just kind of tolerate this issue). It doesn't, however, affect continued operation once running.

I'd pull EVERY fuse and test. Look at connections and re-seat. Do the same for every safety switch. Fragile electrical connection means a voltage drop. Not enough voltage on a circuit will alter switching.

I'd bet that you could find every switch if you put on your detective hat. Wires and link rods tend to meet at switches.

 

[5030]

Is it insured? If it is, roast it and get the payoff on it.