A 2019 John Deere Gator TX; Product ID 1M04X2XDEKM143894; Kawasaki Engine FH601DA53488. Engine Series FH. Engine Model FH601D. Engine Specification FH601D-FS05. Best I can determine the FS05 is a custom engine spec manufactured by Kawasaki for John Deere. The gator performed well for 10 months until a day when it started blowing heavy bluish gray smoke from the tailpipe. Dealer picked up gator and determined the carburetor was defective and replaced the carb under warranty along with changing the oil, oil filter and spark plugs. Dealer did not give any diagnosis other than the carburetor was defective.
Continued using gator around the farm with 2nd carburetor. Every 3-4 weeks gator would begin running rough including some minor backfiring. Each time this occurred, the oil level was well above the full mark and spelled like gas and the spark plugs would be fouled black. Around this time I permanently removed the spark arrestor screen from the tailpipe. Screen was caked with black soot from a constantly rich mixture. Removing the spark arrestor screen did not improve anything. Dealer picked up gator again and eventually installed new carburetor #3. Same pattern continued with carburetor #3. Oil level rises due to addition of gas in the crankcase and spark plugs heavily fouled by heavy black carbon build up. Dealer came out and installed a hotter spark plug. I think original was NGK BPR6ES and they installed hotter BPR2ES. With the hot plugs, the gator started faster than ever but the now routine gas in oil problem continued. When the gator begins to sputter and backfire, I would change the gasoline diluted oil, filter and spark plugs every 4 - 6 weeks or so. By this time the gator was a couple/three months past the 1-year warranty period. It seems there is a high oil level threshold where the engine starts sputtering, backfires and fouls the plugs. Also seems like the rear plug was always more fouled for some reason. For the record the JD dealer was always polite and did continue some service past the warranty period but did not find and correct a root cause. Their official diagnosis is this buildup of gas in the oil is due to short tripping and said they have never had this problem with another gator
. We also have a 2007 TX with the 13HP single cylinder (FJ400?) and used the same way (same frequency, speed and same short trip driving habit); now has around 2500 hours and never leaked gas into the engine oil. Still runs perfectly but the bed is rusted out. With my choices limited and $10K in a machine with under 600 hours I decided to pull it inside my barn shop and remove the carburetor since doing something during warranty period is no longer an issue. This carburetor is a 2 barrel Nikki. Finding Nikki information seems difficult. The numbers stamped in the Nikki carb body include 9Y06 6A, 150041021, 222-014.
The first thing I looked at with bowl removed is how far the float traveled before lifting the inlet needle enough to stop the fuel flow and this point was past level (past parallel with the carb body). I recognized this float setting was allowing a very high fuel level in the bowl. I think enough to flood the intake. Most of you probably know this float is injection molded plastic so the float tab is not adjustable. The rubber tip on the plastic needle looks new. The seat is part of the "spacer" assembly on this carburetor and also looked good. I estimated a needle 2 mm longer would resolve this problem, but of course without a Nikki technical support person with knowledge and access that is not a likely goal I can achieve. I ordered a new float and it was the same way meaning past level before the inlet needle stops. After thinking about my options I lightly secured the float in a small vise; heated the hinge area of the float using a heat gun and bent the hinge portion to control at a lower level in the bowl. I had made a jig to quickly measure from a fixed reference point so this heat and bend process was not completely blind luck. I checked the float for leaks in a cup of water to make sure I did not create a crack. While I had the carburetor off I drilled and popped out the welch plugs hiding the air/fuel mixture screws. I cut slots in the heads of the mixture screws. I found both mixture screws (remember 2 barrel carb) at 4 turns out and left them at that setting even though that is a very rich mixture based on my past experiences with small engine carburetors. I do not remember ever seeing mixture screws more than 2 turns out on anything. On a side note, I had ordered an aftermarket carb with matching mounting holes and throttle bores, but the throttle and choke linkages are on the wrong side. I didn't notice this in the pictures before ordering. Rather than tackling customizing things at this point I installed the OEM carb I had adjusted the float on. I will save the aftermarket for a future spare option.
After installing the modified carburetor, I changed the oil, filter and installed new spark plugs. I have not mentioned it before, but through the whole process I always checked the air filter and replaced it a couple of times. Never found it dirty but replaced anyway as good standard practice. At this point I also checked the engine compression. 150 front cylinder and 140 on the rear cylinder. I pulled the valve covers and checked lash at TDC on the compression stroke for each cylinder. All 4 valves at .008". An old rule of thumb on multi cylinder engines is the compression should not vary more than 10% different so it is within that specification. Gator started and ran OK. I drove it around a bit, then let it idle for 10 – 15 minutes. After it cooled I pulled both new plugs and they were black. I cleaned the plugs and adjusted both mixture screws 2 turns in from the as found 4 turns out (so now 2 turns out). This time I had to adjust the idle up a bit. Thought about leaning the mixture some more to avoid adjusting the idle up but have not done that yet. After adjusting the mixture screws, I ran the gator for about 20 minutes then pulled the spark plugs. They were not black this time so it seems I am heading in the right direction. I am confident the fuel level in the bowl was too high causing gas to flood the intake and subsequently into the crankcase oil. Adjusting the float resolved that and running it on the path at full throttle tells me the lower bowl fuel level is sufficient for full throttle. Only a period of time monitoring the oil level will 100% prove I found and solved the gas in oil problem. Continuing to monitor the spark plug condition will also be required to confirm the mixture is still not too rich. After these changes when I release the accelerator from full throttle down to idle it takes about 5 seconds for the governor to gain control of the idle speed. In the beginning of that 5 seconds the engine stutters a little but does not die. I have no experience with adjusting governors so maybe I will read up on it and improve that 5 second stutter from full throttle to idle.
Some random thoughts. I have a Scag mower with 600 hours. 24 HP B&S with a 2 barrel carb. Never had any engine or carb issue with it. Not sure of the Scag carburetor brand because I have never had to look at it other than when I clean or change the air filter. John Deere should collect customer complaints and stand behind their custom engine specs with a solution instead of publishing a paragraph on short tripping. I wish I had disassembled the original carburetor that performed OK for 10 months. I think Kawasaki could fix this problem but they will not talk to an individual about the problem once they learn it is on a JD product. Nikki has made quality carburetors since around 1935, but the modern method of a 100% plastic float is questionable due to the inability to adjust the very important carburetor fuel level. How about adding a metal tab to the plastic float that can be adjusted? I saw this in some online pictures. How many times does what happened to my 2019 gator happen to others? Comments of all types are welcome to my post. I want to fix this thing. Subaru Robin has a single cylinder replacement engineered with shaft diameter and length to repower a JD Gator with minimal customization required for around $1200. I know that is lot of money, but the OEM carb for this thing is around $325. If I ever have to replace the engine I certainly would not be interested in the OEM Vtwin. I would probably purchase a used JD Gator with the single cylinder engine but will never purchase another new JD due to being stuck with a problem THAT IS NOT DUE TO SHORT TRIPPING.
Continued using gator around the farm with 2nd carburetor. Every 3-4 weeks gator would begin running rough including some minor backfiring. Each time this occurred, the oil level was well above the full mark and spelled like gas and the spark plugs would be fouled black. Around this time I permanently removed the spark arrestor screen from the tailpipe. Screen was caked with black soot from a constantly rich mixture. Removing the spark arrestor screen did not improve anything. Dealer picked up gator again and eventually installed new carburetor #3. Same pattern continued with carburetor #3. Oil level rises due to addition of gas in the crankcase and spark plugs heavily fouled by heavy black carbon build up. Dealer came out and installed a hotter spark plug. I think original was NGK BPR6ES and they installed hotter BPR2ES. With the hot plugs, the gator started faster than ever but the now routine gas in oil problem continued. When the gator begins to sputter and backfire, I would change the gasoline diluted oil, filter and spark plugs every 4 - 6 weeks or so. By this time the gator was a couple/three months past the 1-year warranty period. It seems there is a high oil level threshold where the engine starts sputtering, backfires and fouls the plugs. Also seems like the rear plug was always more fouled for some reason. For the record the JD dealer was always polite and did continue some service past the warranty period but did not find and correct a root cause. Their official diagnosis is this buildup of gas in the oil is due to short tripping and said they have never had this problem with another gator
. We also have a 2007 TX with the 13HP single cylinder (FJ400?) and used the same way (same frequency, speed and same short trip driving habit); now has around 2500 hours and never leaked gas into the engine oil. Still runs perfectly but the bed is rusted out. With my choices limited and $10K in a machine with under 600 hours I decided to pull it inside my barn shop and remove the carburetor since doing something during warranty period is no longer an issue. This carburetor is a 2 barrel Nikki. Finding Nikki information seems difficult. The numbers stamped in the Nikki carb body include 9Y06 6A, 150041021, 222-014.The first thing I looked at with bowl removed is how far the float traveled before lifting the inlet needle enough to stop the fuel flow and this point was past level (past parallel with the carb body). I recognized this float setting was allowing a very high fuel level in the bowl. I think enough to flood the intake. Most of you probably know this float is injection molded plastic so the float tab is not adjustable. The rubber tip on the plastic needle looks new. The seat is part of the "spacer" assembly on this carburetor and also looked good. I estimated a needle 2 mm longer would resolve this problem, but of course without a Nikki technical support person with knowledge and access that is not a likely goal I can achieve. I ordered a new float and it was the same way meaning past level before the inlet needle stops. After thinking about my options I lightly secured the float in a small vise; heated the hinge area of the float using a heat gun and bent the hinge portion to control at a lower level in the bowl. I had made a jig to quickly measure from a fixed reference point so this heat and bend process was not completely blind luck. I checked the float for leaks in a cup of water to make sure I did not create a crack. While I had the carburetor off I drilled and popped out the welch plugs hiding the air/fuel mixture screws. I cut slots in the heads of the mixture screws. I found both mixture screws (remember 2 barrel carb) at 4 turns out and left them at that setting even though that is a very rich mixture based on my past experiences with small engine carburetors. I do not remember ever seeing mixture screws more than 2 turns out on anything. On a side note, I had ordered an aftermarket carb with matching mounting holes and throttle bores, but the throttle and choke linkages are on the wrong side. I didn't notice this in the pictures before ordering. Rather than tackling customizing things at this point I installed the OEM carb I had adjusted the float on. I will save the aftermarket for a future spare option.
After installing the modified carburetor, I changed the oil, filter and installed new spark plugs. I have not mentioned it before, but through the whole process I always checked the air filter and replaced it a couple of times. Never found it dirty but replaced anyway as good standard practice. At this point I also checked the engine compression. 150 front cylinder and 140 on the rear cylinder. I pulled the valve covers and checked lash at TDC on the compression stroke for each cylinder. All 4 valves at .008". An old rule of thumb on multi cylinder engines is the compression should not vary more than 10% different so it is within that specification. Gator started and ran OK. I drove it around a bit, then let it idle for 10 – 15 minutes. After it cooled I pulled both new plugs and they were black. I cleaned the plugs and adjusted both mixture screws 2 turns in from the as found 4 turns out (so now 2 turns out). This time I had to adjust the idle up a bit. Thought about leaning the mixture some more to avoid adjusting the idle up but have not done that yet. After adjusting the mixture screws, I ran the gator for about 20 minutes then pulled the spark plugs. They were not black this time so it seems I am heading in the right direction. I am confident the fuel level in the bowl was too high causing gas to flood the intake and subsequently into the crankcase oil. Adjusting the float resolved that and running it on the path at full throttle tells me the lower bowl fuel level is sufficient for full throttle. Only a period of time monitoring the oil level will 100% prove I found and solved the gas in oil problem. Continuing to monitor the spark plug condition will also be required to confirm the mixture is still not too rich. After these changes when I release the accelerator from full throttle down to idle it takes about 5 seconds for the governor to gain control of the idle speed. In the beginning of that 5 seconds the engine stutters a little but does not die. I have no experience with adjusting governors so maybe I will read up on it and improve that 5 second stutter from full throttle to idle.
Some random thoughts. I have a Scag mower with 600 hours. 24 HP B&S with a 2 barrel carb. Never had any engine or carb issue with it. Not sure of the Scag carburetor brand because I have never had to look at it other than when I clean or change the air filter. John Deere should collect customer complaints and stand behind their custom engine specs with a solution instead of publishing a paragraph on short tripping. I wish I had disassembled the original carburetor that performed OK for 10 months. I think Kawasaki could fix this problem but they will not talk to an individual about the problem once they learn it is on a JD product. Nikki has made quality carburetors since around 1935, but the modern method of a 100% plastic float is questionable due to the inability to adjust the very important carburetor fuel level. How about adding a metal tab to the plastic float that can be adjusted? I saw this in some online pictures. How many times does what happened to my 2019 gator happen to others? Comments of all types are welcome to my post. I want to fix this thing. Subaru Robin has a single cylinder replacement engineered with shaft diameter and length to repower a JD Gator with minimal customization required for around $1200. I know that is lot of money, but the OEM carb for this thing is around $325. If I ever have to replace the engine I certainly would not be interested in the OEM Vtwin. I would probably purchase a used JD Gator with the single cylinder engine but will never purchase another new JD due to being stuck with a problem THAT IS NOT DUE TO SHORT TRIPPING.
