4300 no start issue.

[kc8ksg]

Last fall my 4300 hst started with not wanting to start after working it all day then letting it set over night. After a bunch of searching I did some testing and found somewhere to try shorting the white wire going to your shutoff solenoid and it will force the plunger back in. I did and it worked, so it seemed my shutoff solenoid was fine and I just needed a thermistor.

It wasn't a big deal to short that wire once and a while so that's what I did, here a few weeks ago it got a lot worse and wouldn't start unless you shorted the white wire so I ordered a new thermistor.

It worked great and fired up every time but twice since I replaced it it won't start. It's a lot better than it was before replacing the thermistor, but still something isn't right, and if you short the white wire it fires up every time which is what has me puzzled.

The only other thing I can maybe think is my shutoff solenoid is getting weak, I might try pulling it off and cleaning it to see if that helps but figured I'd ask and see if anyone had any insight.

Thanks

 

[Harry in Ky]

I've seen a number of questions here regarding Deere tractors and their famous thermistors, and although I believe I understand the concept, I'm not sure I agree with it. If your fuel shutoff has only two wires, one power and one ground, then I guess it's all you have. If it's a three wire coil, with one circuit to pull the plunger in, and the other circuit a low draw hold coil, you may have some options. If by "shorting the white wire" you mean temporarily applying 12v, then you could do this with a simple 4 pin relay. Add in a circuit to supply battery positive to said white wire through the relay and use the start signal circuit to energize the relay coil. Not exactly a "factory" fix, but it will do what your "shorting" proceedure does, and do it every time you engage the starter.

 

[kc8ksg]

It's a three wire with the pull in. Shorting isn't really the correct terminology that's my fault for wording it that way, basically I'm grounding the white wire out. I have thought about running a momentary push button to the white wire to basically do the same thing, but figured if I could fix it the right way first I would, if not do it my way.

 

[BRBurns]

My 4300 would not start yesterday either. It had done that before, but if I let it set a few minutes it would always start. This time it didn't. I didn't know about grounding the white wire. But I did know that it could be the solenoid not getting enough power. So I hooked up jumper cables to my truck, running, knowing that this would get the entire tractor 2 more volts. It popped right off and has started dozens of times since. I need to get a spare thermister.

 

[BRBurns]

It did it again this morning and hooking up jumper cables did nothing. Grounding the white wire did the trick. Going to pick up a thermister today.

 

[kc8ksg]

The thermistor did help but so far since it's been in there it hasn't started and I've had to jump the white wire twice. Before the thermistor it got so bad I had to jump it every time.

There have been a handful of times it hasn't started on the first try and after 30 seconds or so it will fire up, the two times I jumped the wire I only waited about a minute and got impatient and jumped it because I was working and didn't want to waste time to see if it'd eventually start on it's own.

Good luck, hope it fixes yours.

 

[Husaria Farm]

I also have a thermistor problem with my JD 4600. When I removed it and "hot" wired the two wires together it started on first try. Afterward it ran until I shut it off. When I tried to restart using the same method the wires got hot and smoked but no start occurred. Did I do some further damage? I'm expecting a new thermistor tomorrow. If that doesn't work, where should I look?

 

[BRBurns]

I think you probably smoked the fuel shutoff solenoid by hot wiring it like that. I'm guessing it can't Handel the full amperage on the solenoid the full time it is running. That is why they put the thermister there. It gets full amperage for a second or two until the thermister heats up and cuts back the amperage.

 

[Husaria Farm]

Thanks BR. That's what I was afraid of. Next purchase looks like fuel shutoff solenoid.

 

[JD755]

Correct that full time current to the pull-in coil on the solenoid will quickly burn it up. It takes a lot of current. JD has used various schemes such as thermistors and time delay circuits to limit the current to just a brief period. The most basic method was used on my 755. It simply connected the pull-in coil to the starter. Very basic and no problems with electronic components. You should do a repair on yours to make it as it came from the factory, but if not then simply connect the pull-in coil to the starter. No relay required.