John Deere L120 Mower problem

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  #1  
Old 11-13-06, 06:16 AM
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Question John Deere L120 Mower problem

Hi - I am having a problem with the subject mower. After mowing for about 20 minutes, the thing just dies. It seems like it is running out of fuel, but the fuel tank is full. Sometimes, if I put the choke on, it will start and keep running. It almost seemed like the fuel pump was shot. Another clue was that the fuel filter had air in it and not much fuel during this 'episode'.

I thought that the fuel pump might have been the issue, so I put a new one on. I also replaced the filter. The last time I mowed, I still had the same problem though.

The fuel pump is a diaphram pump (I think) and it works off of vacuum from the engine. It is possible that I lose vacuum after the engine heats up, but I don't know how to check that.
I am not even sure I am on the right track.

Any help would be appreciated here. I have been diddling around with this mower for a while and can't seem to figure it out. These things are so basic, however John Deere seemed to have gone nuts with putting interlocks and 'cya' stuff all over this mower. What's next - rubber blades?
 
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  #2  
Old 11-13-06, 07:37 AM
Azis
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Try loosening the fuel cap next time it dies. The problem sounds like a plugged vent in the fuel cap. This seems to be more common with rear mounted fuel tanks.
The more fuel in the tank, the more the problem will persist.
If this solves it you may be able to clean out the vent in the cap with compressed air.
I think JD is pretty proud of those cheap fuel caps.
 
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Old 11-13-06, 11:37 PM
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Another thing you might have a look at is the fuel line coming from the tank. I have seen these have some fiber plug in the fuel line right at the tank nipple. Looks like the filter out of a cigarrette stuffed into the fuel line. I don't know what the intent was here, or if it's still done, but it causes this problem.

Imagine how long it took me to learn about that little tidbit...LOL!
 
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Old 11-15-06, 08:28 AM
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Thanks for the tip - I will check the 'plugged' line and the vent.

I did put compressed air in the tank to see if the line from the tank was clogged. The strange thing is that when I took off the fuel line from the fuel filter, there was no gas coming from the tank. As soon as I put some compressed air in the tank, the fuel started to run freely. Unfortunately, that only temporarily fixed the problem.

Thanks again - I will let you know how I make out.
 
  #5  
Old 11-15-06, 11:55 AM
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What engine do you have?
I dont think fuel should readily flow to the filter, if equiped with a fuel pump. Being able to force fuel through the line by pressurizing the tank I would think verify the line is prolly not plugged.
 
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Old 11-15-06, 05:23 PM
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When I ran across this problem on the mower with the plugged line, gas would run out the fuel line, but slowly. Compressed air made it come out quickly. The problem was, gas wouldn't flow fast enough to keep the carb full, so the mower would run for awhile until the fuel in the line ran out and the restriction slowed the flow enough that the carb bagan to gradually starve for gas until it died. You could let it sit for awhile, and it would start back up and run off the fuel in the line again.
 
  #7  
Old 11-17-06, 06:08 AM
Azis
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Cheese was that the same model? The fuel pickup on the L120 shows to come out the top of the tank...?

http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt
 
  #8  
Old 11-17-06, 06:25 AM
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Cheese describes exactly what is happening with this mower.

Cheese - how do I remove that 'fiber filter' in the fuel line? the tank is underneath the seat and is surrounded by the mower chassis. Do I have to take everything apart or is there an easier way to get at the fuel line pickup in the tank.

The L120 fuel line pickup does come out of the top of the tank. I would have expected a 'siphon' action when I disconnected the 'main' fuel filter, but fuel does not run out when this happens. It's very strange.
I am going to check it this weekend as I didn't have time this week and thankfully, the grass is not growing that fast this time of year!
 
  #9  
Old 11-17-06, 08:52 AM
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I have done one similar and the tank required removal. It will come out with just a bit or contorsionist. The illustrated parts list does not show but I think there are 4 or 6 bolts that secure the tank. With the fuel lines removed and the tank drained, it should come out from the bottom. The fuel pickup is held in with a grommet.
The one I did had all of the fuel line cracking and brittle from the tank to the carb. The tank also had similar debris in it.
 
  #10  
Old 11-26-06, 07:36 AM
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Well - I think I finally fixed this problem (with the help of this forum of course). The fuel cap vent hole was plugged with a white-ish looking substance. I took the cap apart and cleaned it up. Now the mower runs fine without starving for fuel.

I must say that I've never run across this problem before. Thanks for the tip.
 
  #11  
Old 09-23-10, 09:19 AM
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Cool john deere

I also had the gas straving with my l118. The gas cap was pluged. Its raining now, hope to try it it out this week end. Will let you know if this does it. Thanks
 
  #12  
Old 11-04-12, 08:05 AM
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unbelievable! I was mowing the lawn for the last time this season, and halfway through the job, the tractor quit. I could hear it starting to run rough, like it does when the fuel is empty. Looked down and confirmed the tank was almost full. Fiddled around with a few things before determining the engine wasn't getting fuel. The nice design of the JD fuel filters allow me to easier determine fuel flow. After awhile I resorted to the best troubleshooting tool - the internet - and found this post. Surely it couldn't be ~that~ simple. But sure enough, cleaned out the fuel cap vent with a toothpick - and WOW! I saw the fuel start flowing through the filter and it started right up. Still can't believe it was that simple - but glad it was! really did not want to have to take the tractor apart in the cold, windy weather today! Thanks for the tip !
 
  #13  
Old 11-04-12, 08:39 AM
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Hello mlebied. Welcome to the Do-It-Yourself Web Site and the Small Engine forum.

Yep. Very often a problem like you described is that simple to fix. A plugged air hole in the vent cap. And searching the site here in this forum very often provides the solution and/or a list of possible causes and all or every possible correction needed....

Thanks for searching the forum and reviving an old thread. Old but still valuable info contained with in it. Almost every possible small engine problem and or condition has already been asked in a post and replied to (addressed) on this site.

Glad you found our site, joined up and found the solution to the problem.

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  #14  
Old 04-13-13, 09:43 AM
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Once again proof that the Internet is for more than porn! This thread saved me from replacing my fuel pump on my L120. Fuel cap unplugged adn back online.

Thanks!
 
  #15  
Old 05-16-13, 08:54 PM
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Simple fix does the job

Should have checked here first!!! Worked on my L120 for 3 days pulling stuff apart and cleaning fuel lines, working on the pump, etc. It would run for 5 min then die... nothing was working... drilled out the hole in the center of the gas cap (and made it a little larger), made sure the holes in the rubber flap inside were clear... a whole 5 minute job in all... presto! My mower is back in business. Awesome suggestion/tip... thanks.
 
  #16  
Old 06-30-13, 12:21 PM
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Unhappy Tried that...

I'm experiencing the same problem... the L120 runs rough. I've removed the fuel cap entirely (while the machine was stationary and running at full throttle) to see if that would fix the problem, but that it didn't. Also, I've cleaned the fuel cap itself.

Any other suggestions? Thanks ahead for whatever help you can provide.

Matthew
 
  #17  
Old 06-30-13, 05:36 PM
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Did you replace the fuel filter?
 
  #18  
Old 05-26-14, 08:24 PM
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It worked

I have a John Deere L118 and had the same problem. I changed the fuel filter and then the fuel pump with neither one fixing the issue. Finally I found this post and low and behold......it worked. I was able to use my air compressor to clear out the white gunk which had formed on the gas tank cap. Thanks for the post!!
 
  #19  
Old 05-27-14, 02:58 AM
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Looks as if 8 year old threads are valuable. Glad it provided you with good info. Welcome to the forums!
 
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