JOSE.JIMENEZSOTO18 6 Posted November 17, 2020 Minimum sensor working If there is fuel pressure Compression is 70 PSI Check the electronic injection sensors and they are working, there are no reading codes, I don't know what to do anymore, not if I'm missing something, it's the first time I've had a problem like this Share this post Link to post Share on other sites
TBRider 1,411 Posted November 17, 2020 What year is your 420? Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted November 17, 2020 8 minutes ago, TBRider said: What year is your 420? 2016 32,000 km The machine starts with sudden throttle pulses and when the accelerator is held down it stays on. When you fully release the throttle, it shuts off Share this post Link to post Share on other sites
jeepwm69 7,783 Posted November 17, 2020 Check the IACV valve on the top of the throttle body. It's held on with two tamper proof screws. I remove those with vice grips, and clean it. When holding the IACV in your hand, when you turn the key on it should spin one way, then the other. Clean it thoroughly with starter fluid and then put it back on, see if it changes anything. That IACV controls your idle, "choking" the machine when it's cold. 4 Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted November 17, 2020 1 hour ago, jeepwm69 said: Check the IACV valve on the top of the throttle body. It's held on with two tamper proof screws. I remove those with vice grips, and clean it. When holding the IACV in your hand, when you turn the key on it should spin one way, then the other. Clean it thoroughly with starter fluid and then put it back on, see if it changes anything. That IACV controls your idle, "choking" the machine when it's cold. The IACV works, it turns back and forth, but the atv has the problem in cold or in heat. When the problem started the first thing I did was look for the fault codes, then check for spark, then went to the throttle body and cleaned the IACV. The ATV does not start easily, I repeat, it starts only if you give sudden movements to the accelerator and it keeps its engine to minimum, as long as you keep the accelerator a little depressed. I thought about compression, but yesterday I did the check and it gives me around 69-70, the honda manual says it is 73, therefore I do not see it very far from its standard, I rule out the compression problem. At the moment, all I need to check is the fuel system. Although I don't know if I'm missing something Share this post Link to post Share on other sites
jeepwm69 7,783 Posted November 17, 2020 Have you changed the fuel filter? That would be my next step. Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted November 17, 2020 1 hour ago, jeepwm69 said: Have you changed the fuel filter? That would be my next step. Done, I just cleaned the pump and it still does not work normally. Even in the organization we will have 3 identical ATVs, so change the entire fuel tank, to make it even safer and still not work well. Do you think maybe I had an error measuring compression? It should be noted that we have 2 machines with the same drawback and almost the same mileage. New spark plugs, clean filter. Share this post Link to post Share on other sites
jeepwm69 7,783 Posted November 17, 2020 Sounds like a fuel delivery problem to me, rather than a compression issue. Any chance you filled them up with bad gas? Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted November 17, 2020 31 minutes ago, jeepwm69 said: Me parece un problema de suministro de combustible, más que un problema de compresión. ¿Alguna posibilidad de que los haya llenado con gas malo? Yeah I thought that too, but chances are slim or nil, when swapping the fuel tanks of a good ATV for a bad one, the bad one still didn't work properly, while the good atv started without any problem. My next step will be to check the ignition system, if it doesn't resolve it, I think I'll inspect the carbon build-up inside the engine. Share this post Link to post Share on other sites
jeepwm69 7,783 Posted November 17, 2020 Try swapping the coils from one bike to another. Share this post Link to post Share on other sites
Misterclean 420 Posted November 17, 2020 It still sounds like the IACV to me. Clean it better a second time. Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted November 18, 2020 4 hours ago, Misterclean said: Todavía me suena como el IACV. Límpielo mejor por segunda vez. Friend I thought that at first so I decided to check the throttle body sensors with the Honda manual, still not working properly, I got desperate and thinking that I could omit something in the analysis, I changed a complete throttle body just like with the pump of fuel and ironically, the same thing happened. I am looking for help, because the truth is I am running out of options They're still on the table: ignition system, and I don't know why, but I still haven't ruled out compression. Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted November 18, 2020 5 hours ago, jeepwm69 said: Intente cambiar las bobinas de una bicicleta a otra. In my country it is already night, tomorrow I will try to analyze the ignition system and I will let you know Share this post Link to post Share on other sites
Misterclean 420 Posted November 19, 2020 (edited) Find a way to check spark at the spark plug while it is running. This procedure will determine spark. Also you can spray some Carburetor cleaner in the throttle body when it is running poorly. If it runs better then it is a fuel problem. I seriously doubt it is a compression problem however there is a very small chance that a valve is sticking at higher engine speeds. Edited November 19, 2020 by Misterclean 1 Share this post Link to post Share on other sites
oldmxrider 76 Posted November 20, 2020 I know it is a long shot but have You checked the SENSOR ASSY., AIR TEMPERATURE Part# 37880-RE1-Z01 Had a race bike last year that was having crazy start and run problems after too much time spent found the air sensor was causing the problems. 1 Share this post Link to post Share on other sites
toodeep 1,760 Posted November 20, 2020 If you have the tester I would check the pulse generator. Also make sure the battery cables are clean and tight, these newer machines are very voltage sensitive. 4 Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted December 26, 2020 Hello everyone. Sorry to be absent. In conclusion, I just had to clean the combustion chamber. Thank you all very much, happy holidays ... 3 Share this post Link to post Share on other sites
Misterclean 420 Posted December 27, 2020 I think your response was translated poorly. I don't think the combustion chamber was dirty. Please try another translation. We want to know the answer to your problem. Thanks. 1 Share this post Link to post Share on other sites
JOSE.JIMENEZSOTO18 6 Posted December 27, 2020 2 hours ago, Misterclean said: Creo que tu respuesta se tradujo mal. No creo que la cámara de combustión estuviera sucia. Intente otra traducción. Queremos conocer la respuesta a tu problema. Gracias. Hello, as I mentioned before, the combustion chamber (Piston, Valves), was full of carbon. Therefore, it gave small, but very small leaks. I'm still baffled by the compression test, which was good, but that was the state anyway. And the truth is that I checked, since I had two Honda 420 with the same problem, at the moment both are rolling. I add that, my state or city has a dry climate and a lot of dust in summer ... Greetings from Costa Rica, my translation a little bad, but I still don't speak English very well and I have to help myself with translators and dictionaries. 3 Share this post Link to post Share on other sites
shadetree 6,036 Posted December 27, 2020 33 minutes ago, JOSE.JIMENEZSOTO18 said: Hello, as I mentioned before, the combustion chamber (Piston, Valves), was full of carbon. Therefore, it gave small, but very small leaks. I'm still baffled by the compression test, which was good, but that was the state anyway. And the truth is that I checked, since I had two Honda 420 with the same problem, at the moment both are rolling. I add that, my state or city has a dry climate and a lot of dust in summer ... Greetings from Costa Rica, my translation a little bad, but I still don't speak English very well and I have to help myself with translators and dictionaries. personally ?, i think the compression is a tad on the low side. 1 Share this post Link to post Share on other sites
spock 46 Posted December 28, 2020 Yeah, even if the compression is sufficient to run it could have worn out oil rings. This would explain the carbon and poor performance. Anything that runs in dust a lot and has pretty high mileage is due for a new top end (piston rings for sure)! Share this post Link to post Share on other sites