JD 4400 CUT cranks but no start

[68BULLITT]

Well I went to start her up this morning. She was cranking but no start. Usually if I can't get the tractor to start it's something stupid and then everything is fine. But for some reason that isn't the case this morning. She worked fine all day yesterday splitting wood, put away last night everything was fine. I checked the oil and hydraulic fluid(which was a little low) topped it up and then went to start. I can feel/hear the fuel shutoff solenoid clicking. The pedals are where they're supposed to be (neutral position) I checked that switch under the floor that the fwd pedal rides against. It is engaged against the pedal. I'm probably missing something but I really need to get her back in service today since I've still got a lot of wood left to split. Thank you all in advance guys!

[kennyd]

This post is in the AG forum (larger tractors). Do a search in the regular JD forum for the term "thermistor" for lots of reading, sounds like this may be your problem.

[68BULLITT]

Dirty fuel filter, she's running fine now

[68BULLITT]

Well so much for that. Now I'm really scratching my head. Like an idiot after hours of trouble free use, I shut down the tractor for a quick second and back to the no start condition. She'll crank but no fire. I pulled the fuel filter and isolated that it can't be that since it still wouldn't fire. I figured I might have air in the lines after that but she never even sputtered. I moved on to the lift pump (which was more simple than I was expecting) and that was fine. It can't be the fuel shut off solenoid so far as I can tell since I can feel/hear it click when I turn the key. I also don't believe it's the thermistor since it was running just fine a few moments before and was running fine all day yesterday. The old filter had nasty crap growing on it so I'm wondering if I have a partially occluded line. There are a few other things that I noticed. First when I opened up the fuel line from the lift pump to the filter, the fuel seems to trickle out. When I manually prime the lift pump the fuel seems to flow at least twice as much. Also I cracked open the #3 delivery valve line to check for fuel and I'm not getting any fuel there. I'm wondering what else to check or re-check, but I need to put this machine back into service ASAP! Thanks again guys

[68BULLITT]

It turns out that it's the fuel shut off solenoid that's giving me fits. More specifically it's the o-ring at the back of the injection pump that's supposed to keep oil out of the solenoid. Again it's supposed to but it isn't. Once the oil gets behind there it gums up the plunger of the solenoid and prevents it from fully retracting thus the no start condition. I cleaned the solenoid Monday put it back in and ran it all day. It was running fine today too until I got my **** hand caught by a log and had to power it down. After that she wouldnt start so I already had my suspicions about that o ring. Sure enough it did it again. What have y'all done? I was thinking of replacing the oring with a slightly thicker one since it looks like there's some room around the solenoid (which is probably why this happens in the first place). I hope this helps anyone else with this series tractor and these symptoms.

Cheers,
Lou

[mflippin]

Same problem with JD 4600. Pump man says oil level shouldn't get that high in pump. I'm looking for answers too.

[mechanic327]

It's the thermistor, solder in a new one and it will be fine. It isn't the oil holding it back.