485x mower no start when warm

bill finn

Member
My sister and brother each own a john deere 485x. they both are experiencing a no start after an hour of run time during summer heat. Not so much in the fall of the year. My brother claims he removes the air cleaner and cracks the fuel cap and his mower cranks a bit then starts. My sister gives hers an hour to sit and it starts. Does anybody have an idea what would cause this? maybe fuel pump? is the pump electric or vacum
 
Can't help with that 485x number as given, the <a href="http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt" target="_new">parts catalog applet</a> can't make heads or tails of such a number - you'll have to get the real model number first.
 
Lucky I found it without too much trouble, X485 shows several engine types by number - you'll will have to get both to do this right, something along the lines of FD750D with other numbers such as AS12, BS12, CS12. Once you have that information, you can get the proper replacement in tank fuel pump if it has died. At these prices, I would make VERY sure it's not just a blown fuse or other simple and cheap fix. I would also buy a $16 eBay automotive one rather than pay these prices. If it actually needs 40 psi for injectors, I know you can find a good quality Bosch pump at rockauto for a 96 acura integra 3 door hatchback without VTEC engine for around $50.

<image src="http://forums.yesterdaystractors.com/photos/mvphoto25284.jpg"/>

<a href="http://www.greenpartstore.com/John-Deere-Fuel-Pump-Fuel-Tank-Sender-Assembly-AM135285.html" target="_new">Sample only</a> [b:654c4848f0] DO NOT BUY[/b:654c4848f0] as this might be the wrong one. I'm not psychic after all, but I do Ok with html.

And it appears you are faster at replies than I am with html toys.
Boy, I'm stumped and stunned all at once. I had no idea garden tractors were along this far, it could be just about anything if it's got a real computer running injectors etc. I had no idea how far they took this, does it have an OBDII scanner port like most cars do under the driver side dash? Have an auto parts store read the codes? I'm half kidding here, if it had any such thing it would be Mother Deere proprietary and we will never know what any port tells about anything. If so, you are stuck at the mercy of the stealers JD shop unless there is a web site for fellow X485 owners in the same boat and they have it figured out. Try youtube?

Individual sensors like that can often be found to be good or bad by measuring the voltage they are sending the computer, the sensor itself may have a bad ground causing all this. Bad connectors also a problem area. Not knowing any more than I do at the moment, if I had to, I would start by attempting to find out what resistance the sensor has with engine off and disconnected from the tractor, use a hair dyer on it from two feet away and see if the resistance can be seen moving - if it moves, it might be good, don't get it too hot. This actually proves nothing though since I don't know how it works in the first place.

Give me some time to dig more in general, but do get back with those engine numbers for a decent parts match when and if anything bears fruit here.
 
Search for 'X485 engine surges' and enjoy? One easy to find hit suggests that you measure the fuel pump pressure. His was 17 psi and when he pinched the return hose it did not change. He took out the fuel pump to find a loose clamp which he tightened, now he has 25 psi and when the return line is pinched it goes right up to 70 psi. Says it looks like the factory just didn't pinch the crimp type clamp hard enough. A lot of hits out there on this, you should have googled before coming here. I'm still stunned though.

Nice tractor too.
 
I can tell you from experience the service man at John Deere knows the fix but they will not share this unless you trade there service or parts. They been so instructed to cash forward all the information. I found them not to volunteer any information without sales. Now having said this you might plunder through this post and figure it out. I had a problem with my JD990 4 cylinder diesel and it was only a slight vent clogged on the fuel assembly. It would not supply fuel like a vapor lock. I suspect something similar in your devices. As air pressure from heat is building up it cannot vent. The fix is cleaning and you can use a bread wrapper tie after peeling off the plastic and work it through the vent holes. Naturally a $$$$$$ part would also solve this. You got build up from this new fuel....my 2 cents....Chuck in Hartford
 

Sometimes phantom hot start problems are caused by valve lash that is too tight.
Hot intermittent electrical/electronic problems can be challenging to troubleshoot.
I ran around in circles troubling shooting a LX188 that would start and run about 1/2 second.
I learned all over again not to trust people. One of the boys had replaced the ignition module but the well hidden chassis connection was left leaning against the engine block instead of being bolted down. Fun times.
A can of circuit cooler can sometimes chill a suspect component back into operation.
 

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