I have a John Deere Z425 zero turn mower with a Briggs & Stratton engine. The engine is model: 44R677, type: 0015G1, code: 140120YG. The mower runs perfectly fine for about 15 minutes then will sporadically begin missing/stuttering. It never dies but the longer I mow the more frequent the missing/stuttering becomes. It seems to be more frequent when engine is under load such as increasing speed after a turn or going up a hill. The increased load of mowing taller grass seemingly has no effect. Here is what I have tried so far with no success (some is just routine maintenance but I figured I would include it anyway). Changed oil, replaced air cleaner, replaced fuel filter, replaced spark plugs, checked/adjusted valve clearance, replaced vacuum hose running from valve cover to fuel pump, verified that hole in gas cap is clear and even tried loosening gas cap for a while. It only seems to be getting worse. I have no idea what else to try. Anybody have any suggestions? Thanks!
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John Deere Z425 with Briggs & Stratton Engine stutters after warm up
- Thread starter dslankard
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Export threadbertsmobile1
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You need to work out if it is a fuel or electrical problem
I use an alternative fuel tank to do this and some orange in line spark testers .
If the mower runs through the alternative tank with no problems then I know there is a fuel supply problem .
If the spark testers flash erratically then I suspect an ignition problem
The mot common causes for this
1) debris floating in the fuel tank partially blocking the fuel outlet
2) delaminated fuel line
3) engine overheating from debris around the cooling fins under the blower housing .
I use an alternative fuel tank to do this and some orange in line spark testers .
If the mower runs through the alternative tank with no problems then I know there is a fuel supply problem .
If the spark testers flash erratically then I suspect an ignition problem
The mot common causes for this
1) debris floating in the fuel tank partially blocking the fuel outlet
2) delaminated fuel line
3) engine overheating from debris around the cooling fins under the blower housing .
Thank you for your reply. I forgot to mention that it also seems to stutter more when I am on an incline with the left side lower than the right. Do you think that might indicate more of a fuel flow issue?
I am pretty meticulous about keeping inlets clean of any debris so I know that number 3 on your list is not the problem. I am wondering if it might be a good idea to just replace all of the fuel lines and take the fuel tank off and clean it out really well. Do you think that might be a good start?
Also, is there any chance it might be the fuel pump or would that just go out all at once and/or be more consistent about running poorly?
Thanks so much for your input.
I am pretty meticulous about keeping inlets clean of any debris so I know that number 3 on your list is not the problem. I am wondering if it might be a good idea to just replace all of the fuel lines and take the fuel tank off and clean it out really well. Do you think that might be a good start?
Also, is there any chance it might be the fuel pump or would that just go out all at once and/or be more consistent about running poorly?
Thanks so much for your input.
bertsmobile1
Lawn Royalty
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There are so many if's but's mayby & perhaps that it is not funny
This is why I ask you to do the simple test first
I could write 33,000 words & still not hit on your problem
It is never a goos idea just to start replacing things willy nilly
You find the problem then correct it followed by looking for the next one
Replacing the fuel line to the tank is difficult and unless you have proper fuel line extractor pliers you stand a good chance of breaking the outlet tube which still does not clean debris out of the tank .
This is why I ask you to do the simple test first
I could write 33,000 words & still not hit on your problem
It is never a goos idea just to start replacing things willy nilly
You find the problem then correct it followed by looking for the next one
Replacing the fuel line to the tank is difficult and unless you have proper fuel line extractor pliers you stand a good chance of breaking the outlet tube which still does not clean debris out of the tank .