X300 fs600v surging and wont stay running - SOLVED

xesvuli420

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Hello everyone!

Ive exhausted all my normal resources so I went looking for a new one and found this place for hopefully some fresh ideas. I have a sick mower Im trying to get back running good again. A few weeks ago it started missing a little bit while I was trying to cut a yard. It was puffing a tiny bit of black smoke once in a while so I figured it was either a fouled plug, or intermittent wire issue. I continued mowing since I only had about 20 minutes left on the yard. By the time I was done, it couldnt even pull itself up my dump trailer without dying. I brought it home and parked her for the night. The following day I wanted to mow my yard, so I went to crank the sick mower to move it out of the way. I have a spare x354 so a dead mower isnt a huge issue. Wierdly however, she fired right up. Actually ran so good I mowed my entire yard and a few extra areas. Not a single hiccup. When I finished mowing, I moved her to her normal spot and not in the grass since it seemed she was back to normal.

Fast forward to the next mow date and the spitting, sputtering, and smoking was all back again. I did notice something this time though. If anyone can explain it, please do. Even though the mower was running terrible, and missing, when you turn the key to off, for the 2 second delay it takes before the mower kills the engine, it ran perfectly. Every single time. Turn the key switch to ON and it sounds and runs like crap... turn the key to off and it would run perfect. Turn the key back to on before it shuts down and it would quickly start to die again.. back off, and its smooth as silk until it cut itself off. Something to do with the solenoid I bet. I parked her in the garage and took my working mower to do the job. When I got home I gave her 2 new plugs. Didnt help. I pulled the wires and checked for spark. No problems there, and each time I pulled the wire on either cylinder, the engine increased its miss. Satisfied with the ignition system for now I moved on to the carb. First I wanted to test operation of the shutoff solenoid. It worked as it was supposed to. So I went ahead and pulled the whole carb for tear down and rebuild. After a thorough cleaning of all the components, I reinstalled the carb new gaskets and all. Once gas had filled the bowl, I could tell the miss was gone.. but sadly in its place, was now engine surging.

After manually manipulating the plate on the carb that the governor controls, and mostly covering the intake pipe, I could get it to run semi correct for a moment or two. But left to its own, it quickly dies. I changed the fuel filter and verified the fuel pump was in fact pumping. I also gravity fed the carb just to make sure the fuel system wasnt affecting the mower in anyway. Doubting my work, I kept telling myself its got to be still in the carb, maybe i missed the blockage, or installed something improperly, or something. To try and isolate the issue, I ordered a cheap but highly rated carb off of amazon. This would either fix my problem, or exclude the original carb from the "suspects list".

Today after installing the new carb, I still have the same issue.

Now as it sits, It wont start without full throttle, and even then it surges.

Anyone here ever seen anything like this? Ill admit, im not really sure what to check next. I could sure use some help here!

Thanks for taking the time to try and help!
-Shane
 
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bertsmobile1

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A few things worth looking at
1) replace the fuel solenoid on the carb with a short bolt, thus taking the solenoid & solenoid wiring out of the question.
2) rig up an external fuel tank and the minute it plays up switch to the alternative tank. problem goes away = obstruction to the fuel supply
3) check that the fuel solenoid is working. Remove the blower housing and remove the kill wires from the magnetos, make sure it is not laying on the head or can get fouled in the fluwheel or starter.
Replace the blower housing & go mow. Problem goes away you have a safety switch or associated wiring problem.

I can not strongly enough recommend buying the JD Technical manual for your mower .
After reading it you will be here telling people how to fix their mowers .
 

xesvuli420

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Hey bert! Thanks for your reply. Unfortunately all your suggestions have already been attempted. Unfortunately none hVe been any help. Ive already tested the fuel cutoff solenoid. Its working properly. Nice and springy without any resistance. I may do like all the others and bolt it up to bypass it, but for this problem, its not at fault. Key on it sucks down just as it should. Also i have a pdf manual. great place for specs and tolerances.. great tip! Also the problem persists on or off my gravity fed aux tank. I sure appreciate the ideas. Good to see ive already done the things suggested.. means im doing my troubleshooting correctly. Any other ideas? Thanks again!
 

bertsmobile1

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Hey bert! Thanks for your reply. Unfortunately all your suggestions have already been attempted. Unfortunately none hVe been any help. Ive already tested the fuel cutoff solenoid. Its working properly. Nice and springy without any resistance. I may do like all the others and bolt it up to bypass it, but for this problem, its not at fault. Key on it sucks down just as it should. Also i have a pdf manual. great place for specs and tolerances.. great tip! Also the problem persists on or off my gravity fed aux tank. I sure appreciate the ideas. Good to see ive already done the things suggested.. means im doing my troubleshooting correctly. Any other ideas? Thanks again!
You may have a random short on the solenoid wire so removing it excludes this problem
Removing the kill wires to the magnetos rules out a wiring fault
Afte that you are left with either a faulty magneto
Faulty carb
Valve problems.

The cam lobes & profiles are identical so you can measure the valve lift & duration, should be the same both sides if the lash is the same.
All valves should be at the same height when fully closed, so worth a measure to rule out a moving valve guide.
 

xesvuli420

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Thanks again Bert!

A random short would short randomly, not every single time. My problem is every single time. Cant get it to run right at all. Ive already verified the solenoid works, at least enough to start the engine. I understand the solenoid is a repeat offender for issues, but this time im confident its not. Lets look in a different direction.

Could you tell me more about the magneto kill wires, maybe the colors to identify them. I can definitely remove those and test the issue again.

Again, im using 2 carbs to troubleshoot so we can rule a bad carb out at this point.

Lastly, if no other ideas are out there, and the magneto test doesnt help, i suppose its time to check the valves. I wouldnt expect a failure on a 125hr unit, but its more than possible. I just want to hit every avenue.

Im actually surprised theres been no mention of the governor or its spring.. Im wrong almost daily, but my guess is something in this system.

Thanks again for all your time! Im hopeful that we stumble upon the culprit soon.
 

bertsmobile1

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Having re read your original post I realize the information I gave you was wrong.
Your only problem at this point in time is surging & I was off looking at the original problems.

Surging is always caused by an air : fuel ratio that is too lean to maintain a constant speed.
Only 2 ways this can happen
1) carb not supplying enough fuel
2) air entering the engine after the carb venturi tube has added the fuel.

To test for the latter, start the engine, hold the governor arm at whatever place to obtain the fastest smooth speed.
Saturate the manifold area with WD 40 , do not use a spray can unless you think singed eyebrows look sexy .

Engine changes speed or blows white smoke = leaking manifold.
As you will only be doing it for a few minutes it is fine to do this with the blower housing off to get better access to the manifold & head.
 

xesvuli420

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Wow! What a great post! Thank you again, those are some steps im excited to try. Ill post back after I get the reaults!
 

xesvuli420

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Well Bert, Im am happy to come here today and report I have solved the issue. Sometimes in life we just dont dig far enough into our problem the first time. Yesterday I was swapping the cheap carb back to the oem carb since I had verified the carb wasnt the issue, and after I got it off, for the first time in all the removals, i decided to also pull the spacer. I hadn't before because my attention had been on the carb and its gaskets, the spacer looked fine and was good and stuck to the intake, so I never disturbed it. Yesterday just to be thorough, I did. As soon as i popped it off, I found another torn gasket between the spacer and the intake. Replaced it, reinstalled everything, and after the bowl filled up with gas, she give a final few pops and sputters and shes been purring like a kitten every since. Ive been chasing this surge for days, numerous times on and off with the carb rechecking my work, and the entire time, I was literally 1 spacer away from the issue. Aye caramba. What doesnt kill us makes us stronger right? Anyways, thanks for being a part of this journey with me, and to anybody else thats here hunting a new suggestion to why your mower is still surging and youve already cleaned the carb, pull the spacer too! lol.
 

gainestruk

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Thanks for the update, most never come back and tell us what happened !
 

smalltowntex

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Hello everyone!

Ive exhausted all my normal resources so I went looking for a new one and found this place for hopefully some fresh ideas. I have a sick mower Im trying to get back running good again. A few weeks ago it started missing a little bit while I was trying to cut a yard. It was puffing a tiny bit of black smoke once in a while so I figured it was either a fouled plug, or intermittent wire issue. I continued mowing since I only had about 20 minutes left on the yard. By the time I was done, it couldnt even pull itself up my dump trailer without dying. I brought it home and parked her for the night. The following day I wanted to mow my yard, so I went to crank the sick mower to move it out of the way. I have a spare x354 so a dead mower isnt a huge issue. Wierdly however, she fired right up. Actually ran so good I mowed my entire yard and a few extra areas. Not a single hiccup. When I finished mowing, I moved her to her normal spot and not in the grass since it seemed she was back to normal.

Fast forward to the next mow date and the spitting, sputtering, and smoking was all back again. I did notice something this time though. If anyone can explain it, please do. Even though the mower was running terrible, and missing, when you turn the key to off, for the 2 second delay it takes before the mower kills the engine, it ran perfectly. Every single time. Turn the key switch to ON and it sounds and runs like crap... turn the key to off and it would run perfect. Turn the key back to on before it shuts down and it would quickly start to die again.. back off, and its smooth as silk until it cut itself off. Something to do with the solenoid I bet. I parked her in the garage and took my working mower to do the job. When I got home I gave her 2 new plugs. Didnt help. I pulled the wires and checked for spark. No problems there, and each time I pulled the wire on either cylinder, the engine increased its miss. Satisfied with the ignition system for now I moved on to the carb. First I wanted to test operation of the shutoff solenoid. It worked as it was supposed to. So I went ahead and pulled the whole carb for tear down and rebuild. After a thorough cleaning of all the components, I reinstalled the carb new gaskets and all. Once gas had filled the bowl, I could tell the miss was gone.. but sadly in its place, was now engine surging.

After manually manipulating the plate on the carb that the governor controls, and mostly covering the intake pipe, I could get it to run semi correct for a moment or two. But left to its own, it quickly dies. I changed the fuel filter and verified the fuel pump was in fact pumping. I also gravity fed the carb just to make sure the fuel system wasnt affecting the mower in anyway. Doubting my work, I kept telling myself its got to be still in the carb, maybe i missed the blockage, or installed something improperly, or something. To try and isolate the issue, I ordered a cheap but highly rated carb off of amazon. This would either fix my problem, or exclude the original carb from the "suspects list".

Today after installing the new carb, I still have the same issue.

Now as it sits, It wont start without full throttle, and even then it surges.

Anyone here ever seen anything like this? Ill admit, im not really sure what to check next. I could sure use some help here!

Thanks for taking the time to try and help!
-Shane
If you don't have the problem solved, you might consider a different approach. I have a John Deere X324 with FS651V 22HP Kawasaki. My engine did some of the things you mentioned and I tried about all you have tried. No need to take it to the shop. You will be able to solve this problem (maybe). I installed a new Electronic Control Unit. Mine was up under the dash real close to the hour meter. Has about9 or 10 wires going to it. Course it does all kinds of things but when you take it off, you will see the date it was made and this might enter into your problem as well. I thought it was an expensive fix but consider you don't take it to the dealer it is reasonable. About $100. i DO NOT know if John Deere can test your old one or not but I wouldn't give them the satisfaction of checking it. Check out "faulty electronic COntrol Unit" or ECU and I bet it will be worth a shot. Hope it cures the problem.
 
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