Kawasaki does know of the "fix" for it, but it's multi-faceted. One must follow the steps.
1: try starting the engine without touching the throttle pedal. If you start it like an old carburetor, it ain't gonna idle (and kawasaki don't believe me on that...but it's absolutely true)
2: check the engine oil. If over the full mark, it's got hydrocarbon vapors in it and it WILL affect idle quality. Change it.
3:check engine compression. Should be up around 200 psi or more. If low, check valve clearance and adjust as necessary (.010"). Tight intake valves are common, and it causes pulsing in the intake manifold, which confuses the intake air pressure sensor's reading to the ECU.
4: check air filter, especially if the oil level was high. Replace it if it's oil soaked and/or dirty. It too affects idle quality.
5: clean the throttle body. Put a hammer between the gas pedal and the frame above it so that the throttle is "bricked" wide open. Remove the air intake hose from the throttle body. Grab your carb cleaner or throttle body cleaner (with straw). Start engine. It will be running about 4000 RPM which is fine (it's governed). Spray the carb/TB cleaner into the TB until the engine falls on it's face, let it catch back up, repeat this process until you run the entire can of TB/carb cleaner through the TB.
Usually that fixes them BUT every once in a while it doesn't. There is another workaround too but I won't go into it because it requires access to Kawasaki proprietary software, a laptop, and proprietary cabling and adapters-only available from Kawasaki to my knowledge. Real similar to Kubota but different, and not as functional.
93 octane fuel burns real dirty. I know, the makers want you to think that it "cleans" things, but in the combustion chamber it does just the opposite...it loads things up with carbon including the intake valves, valve seats, valve faces, exhaust valves, piston crowns/domes/dishes, etc. 87 octane is perfectly fine for a low compression Mule engine and it is generally recommended. Also the fuel filter should be replaced periodically, it's easy to do, and not very expensive but it requires removal and disassembly of the fuel pump module.
The root issue is application. The 620 engine was originally designed as a generator/mower engine. On that type equipment, it ran at 3500-3700 RPM all day long under a heavy load, which generated a good bit of heat in the cooling and lubrication system. Well on the Mule, the engine IDLES most of the time and has little if any load against it. Total opposite. Big deal right? Wellllll.....if the engine OIL can't get up to 200 degrees+, any combustion byproducts can't evaporate. Engine oil level rises, gets a bunch of fuel vapors in it, and then because of the closed crankcase vent system (sorta a PCV) the engine is now ingesting it's own oil and fuel vapors that have built up in the crankcase, which carbons up the valves and pistons even more, wears the valve faces/seats off, the clearance closes up, pretty soon the engine compression is down, so is power, it won't idle, the throttle body gets gummed up, the intake pressure sensor senses pulsing, and it just overall runs like poo. Additionally, a stuck thermostat will also throw a wrench into the spokes in that they stick OPEN, and the engine won't get hot. Easy to spot using the diag software and a laptop but only dealers have it (to my knowledge), it'll get up to about 130 degrees in the hottest part of the summer and level off. An engine with a good thermostat will get up to 215 or so then drop back to about 180 and repeat over and over again--assuming the fan works as designed and the radiator isn't plugged up with cow/horse/goat poo and/or mud, dirt, hay, grass, chaff, fleas, ticks, dirt dobber nests, carpet, or whatever else. I think I remember one that had a bunch of cat hair across it too, their barn cats slept up on the winch area and the hair that was shed got sucked up by the fan, got wet during operation outside, and turned into a nasty mush that restricted air across the radiator core.
What recall was on the TPS's? I don't remember any but I don't have time to watch every single bulletin that comes out either.
I am habing a huge issue with my 4010 trans 4x4 that seems eeirely similar to what you are talking about.... i posted this in the "KAWI WIDERS" page but i am not getting any traction, do you have any input on what i have going on?
I just bought this 4010 Mule off Facebook, seller said he bought it off a farmer and drug it out of the shed, put a new battery in it, washed it, and posted it. Original statement was that it was not getting enough fuel pressure, It starts, runs ( but slow, as if it was starving for fuel) and goes into forward and reverse, I figured why not! lol..
STEP # 1 -I bought the service manual, read it, determined that if I dont have atleast 40PSI of pressure on the rail i will be running into issues.... so pump it was....
My DFI Indicator light will illuminate at the beginning of ignition turn on, then after 3 seconds it will turn off ( as expected) I have yet to have any light flash from that indicator light.
Fast forward 1 week, I got a fuel pump repair kit off ebay ( replacement pump and filter) to rebuild my pump, I cleaned off the top of the tank ( with a power washer, and i was very careful not to go crazy spraying by the electronics under the drivers side of the front seat), replaced the pump parts ( that was fairly easy) put it all back together, and go to start it, I have great pressure at the fuel rail now! awesome! the old filter was horrible!.... all my problems are solved... NOT
Mule turns over BUT will not idle... it starts, runs for 3-5 seconds, then turns off, almost like the ECM is forcing it to turn off?
If i spray choke cleaner into the air induction tube, it will run off that until the fuel source ( choke cleaner) runs out.. which tells me that I am either not getting fuel through my injectors OR my injectors are flooding out and stuck open?
I mess around with it, I made sure that my lines were clean from the pump to the rail, everything seems to be in check, in my head there should be no reason that it doesnt start and atleast idle... but run better than it was 30 minutes before this?!?!?
Had some family stuff so I had to put this off for a couple days....I redid the carb cleaner test to confirm my plugs/wires/ and crank sensor were all still functioning, I opened the throttle and sprayed choke cleaner in, now it wont even run off of that? it acts like it is backfiring?
SO, now I am very confused... I am going through pages... I still have not indicator light showing codes on the DFI, same solid for 3 seconds at start, and immediately off, so I skip pages 3-36 through 3-39 about the self diagnostics port/ reading codes... (maybe this will bite me in the ass later.... but if its not flashing the ECM doesnt see a problem? right?
I continued on trying to "find a broken wire" It has to be some connection somewhere, a plug, a pin, or broken wire, there is no way it just broke sitting there doing nothing.... I DROVE it into my garage....
Pages 3-40 through pages 3-54 go through testing, replacing, and tracing the wires back to the ECM on the Main TPS, Sub TPS and Sub throttle Valve Actuator, I step by step go through the inspections checklist, testing each wire,I have continuity at each wire back to the ECM for both TPS's. My main TPS passes ALL the tests, my sub TPS passes resitance, and has 4.9V on the incoming wire (blue/red) HOWEVER the ground wire (brown/black) is not receiving anything from the ECM? I double checked that wires continuity to the ecm main harness, and i have a solid connection ( no broken wire) I then went through the checklist of how to test for quality ground and power TO the ECM, that passed with flying colors, everything i am reading is telling me to replace the ECM becasue it is suppose to supply me with ground but is not providing it... I tested this theory by grounding the wire to my chassis, thinking that if my TPS sensor was not being grounded, it could not return an accurate value to the ECM, and if the ECM thinks that the TPS is not working, then it will not let my Mule start.... It was a good idea... but did not work.... I was really pulling at straws there....
I am sitting at the threshold of paying $700 for a new ECU, and before doing so, I am praying that someone can chime in and let me know some tricks to test... It is not my main unit, so i can hold off for a bit getting it working... but at the same time it is in my garage taking up space.
Here is the link to the forum, i also included the entire 2010 service manual on that page if anyone is looking for it
www.kawieriders.com
