Honda Discussions about Honda ATVs.
Sponsored by:
Sponsored by:

Honda TRX 420 ES cold start problem

  #1  
Old 01-18-2009, 05:56 PM
Weekend Warrior
Thread Starter
Join Date: Jan 2009
Posts: 1
Default Honda TRX 420 ES cold start problem

Hi Everyone :

My Honda trx 420 has a strange cold start problem. The battery is always fully charged but sometimes in cold weather, the ATV won't start. Today, I started the ATV before heading out to ice fish and when iIgot to the lake, the ATV wouldn't start. So, I put the ATV in my ice fishing tent and started my heater. Within 5 minutes, the ATV started. Is this a fuel injector problem ? Something is freezing up which is preventing the engine from starting. The temperature was minus 18 degrees centigrade today.

I awlays add a bit of gas line antifeexe to the gas tank.

Len
 
  #2  
Old 01-18-2009, 10:01 PM
Trailblazer
Join Date: Oct 2005
Posts: 32
Default Honda TRX 420 ES cold start problem

I had the same problem with mine when its cold (-10c or colder) no matter how much choke I give it.
So I took the right side plastic off and pushed the primer on the bottom of the carb a few times and she
starts right up!! No matter how cold. I'm not familar with your model, but would assume it's similar as
my 05 foreman.

Seemer
 
  #3  
Old 01-18-2009, 10:40 PM
JeffinTD's Avatar
Extreme Pro Rider
Join Date: Oct 2004
Posts: 3,141
Default Honda TRX 420 ES cold start problem

That would be good advice, but the 420 is electronic fuel injection.

Two things come to mind.

First, make sure you are using an appropriate viscosity oil for the temps you are running in. Also, synthetics have better cold pumpability.

Secondly, assuming it's similar to EFI Rincons, the idle air control may be hanging up. They have some sort of greasy stuff on them which apparently thickens in cold weather. You might try removing the IAC and cleaning it up with some contact cleaner.

Good luck, and let us know how it turns out.
 
  #4  
Old 01-19-2009, 03:08 PM
Gimpster's Avatar
Pro Rider
Join Date: Feb 2004
Location: Bismarck North Dakota
Posts: 1,034
Default Honda TRX 420 ES cold start problem

Jeff is right. Also make sure the right spark plug number is in the quad. Have had some come through the shop that have had the wrong plug in them.
Under the seat above the throttle body is a white-ish plastic cover. Under it is the sensor in question. Remove it, clean the IACv of grease and clean it's bore with carb cleaner and a q-tip. reinstall.
What is happening is the IACV (Idle air control valve) is a stepper motor. When the key is turned on, since this is an open loop type fuel injection system, the ecm needs to take calibration of all sensors each time the key is turned on. When the key is turned on hte IACV automatically goes through it's travel (you should hear a buzzing sound from it when keyed on as it is taking this reading and storing it in the ECM). With any grease or dirt in the IACV bore, it will throw the calibration off giving the wrong air fuel mixture for start up. Many times resulting in too rich mixture after each extreme cold start, fouling a pug.
Another issue to look at is if a valve is too tight. It will cause cold start-up problems as well.
Honda claims there is no cold start issue with these units. While working for the last Honda dealership, I was working with an engineer for this exact problem as tech support had no answers for the problem. While doing tests such as different ECMs ect... I found the trouble starting with them at 16 degrees and below when the unit sets in these temps for 4 hours or more. No matter the weight of oil. They have difficulty starting.
Since this issue was never resolved while I was working with Honda ( I had over 160 unpaid hours of diagnostics on these quads under warranty time, I walked out on Honda dealers), the problem still exists on a lot of 420's out there as you have described. A local Honda tech showed up at my shop one day recently asking if I had found a cure as Honda has no advice for him and claim the problem does not exist to date. When he calls tech line they have no support for the issue.
The issue has also been documented in a select few Rincons. IACV cleaning or replacement has cleared them up though.
Installing a block warmer or hose heater has helped customers I have run across this winter at my own shop. Funny part is once they start up one time cold, they will start every time until setting in the extreme cold for 4 hours or more. It reminds me of a stator issue I found in the late 90's on fuel injected snowmobiles. In the cold, a lighting coil winding in those stators would not supply enough voltage to the ECM in cold temps causing simular issues. This is what I was checking the day I walked out on Honda, to see if I could find a voltage or resistance problem going to the ECM on these units. I'm almost sure the issue lies in this area.
Nuff of my babbling....
Hope some of this info helps you out
Enjoy your 420

----- Gimpster -----
 
  #5  
Old 01-19-2009, 08:03 PM
JeffinTD's Avatar
Extreme Pro Rider
Join Date: Oct 2004
Posts: 3,141
Default Honda TRX 420 ES cold start problem

Following the issue with some Rincons, it also seems that a battery at less than 100% can contribute to poor starting, even though it seems to crank with sufficient speed to start...
 
  #6  
Old 12-06-2015, 07:05 PM
Weekend Warrior
Join Date: Dec 2015
Posts: 1
Default

Originally Posted by Gimpster View Post
Jeff is right. Also make sure the right spark plug number is in the quad. Have had some come through the shop that have had the wrong plug in them.
Under the seat above the throttle body is a white-ish plastic cover. Under it is the sensor in question. Remove it, clean the IACv of grease and clean it's bore with carb cleaner and a q-tip. reinstall.
What is happening is the IACV (Idle air control valve) is a stepper motor. When the key is turned on, since this is an open loop type fuel injection system, the ecm needs to take calibration of all sensors each time the key is turned on. When the key is turned on hte IACV automatically goes through it's travel (you should hear a buzzing sound from it when keyed on as it is taking this reading and storing it in the ECM). With any grease or dirt in the IACV bore, it will throw the calibration off giving the wrong air fuel mixture for start up. Many times resulting in too rich mixture after each extreme cold start, fouling a pug.
Another issue to look at is if a valve is too tight. It will cause cold start-up problems as well.
Honda claims there is no cold start issue with these units. While working for the last Honda dealership, I was working with an engineer for this exact problem as tech support had no answers for the problem. While doing tests such as different ECMs ect... I found the trouble starting with them at 16 degrees and below when the unit sets in these temps for 4 hours or more. No matter the weight of oil. They have difficulty starting.
Since this issue was never resolved while I was working with Honda ( I had over 160 unpaid hours of diagnostics on these quads under warranty time, I walked out on Honda dealers), the problem still exists on a lot of 420's out there as you have described. A local Honda tech showed up at my shop one day recently asking if I had found a cure as Honda has no advice for him and claim the problem does not exist to date. When he calls tech line they have no support for the issue.
The issue has also been documented in a select few Rincons. IACV cleaning or replacement has cleared them up though.
Installing a block warmer or hose heater has helped customers I have run across this winter at my own shop. Funny part is once they start up one time cold, they will start every time until setting in the extreme cold for 4 hours or more. It reminds me of a stator issue I found in the late 90's on fuel injected snowmobiles. In the cold, a lighting coil winding in those stators would not supply enough voltage to the ECM in cold temps causing simular issues. This is what I was checking the day I walked out on Honda, to see if I could find a voltage or resistance problem going to the ECM on these units. I'm almost sure the issue lies in this area.
Nuff of my babbling....
Hope some of this info helps you out
Enjoy your 420

----- Gimpster -----
Your on the right path. After reading your post, I took a hair dryer and heated that Part you where referring to on the carb throttle body for couple minutes and by Golly my girlfriends 420 stared right up. Next is to bring it in somewhere warm and wipe off that electrical grease. Thanks for the info...currently the temp here is -5 but with windchill it's more like -20.
 
  #7  
Old 12-08-2015, 12:43 PM
Extreme Pro Rider
Join Date: Jun 2014
Location: Illinois
Posts: 3,050
Default

Originally Posted by Alaskanoutdoorsman View Post
Your on the right path. After reading your post, I took a hair dryer and heated that Part you where referring to on the carb throttle body for couple minutes and by Golly my girlfriends 420 stared right up. Next is to bring it in somewhere warm and wipe off that electrical grease. Thanks for the info...currently the temp here is -5 but with windchill it's more like -20.
Brrr, I got cold just reading your post lol. I can imagine very cold temps make it harder for any quad to start, even those with efi such as a Rancher 420. I guess if you live in Alaska, temps under zero are the norm every winter. Even down here in Illinois, we managed to get a few sub zero days last winter. So far, the coldest it has been is about 25F. Its almost 60F today, very mild.
 
  #8  
Old 01-27-2019, 08:28 PM
Weekend Warrior
Join Date: Jan 2019
Posts: 1
Default 2009 Rancher AT Fuel Injection Cold weather

I have been stranded 3 times in 0 or below temps. I know immediately when fuel injection does not sound right itís not going to start. Itís not the gas,battery,spark, etc. itís related to ECM not telling injectors to push fuel in. I donít know what to do? I will follow Glimpsters recommendations. Thinking of selling and getting a carb model. If unit is not reliable and I canít trust it that stinks. Any other thoughts appreciated. Today it was -6 at start up. Drove out 2 miles on a Wisconsin lake fished for hour or so went to move dreaded no fuel sound. Buddy had sled to tow. Ruined fishing day. Got home 5 min with Reddy Heater on it fired up. Frustrating. Thanks guys.
 
  #9  
Old 01-28-2019, 02:30 AM
Extreme Pro Rider
Join Date: Oct 2013
Location: Lancaster England
Posts: 3,727
Default

It never gets very cold here in England, but we have had problems with the slider on that ICAV, sometimes giving a high idle speed, sometimes overdoing it and giving an idle so slow it stops. I would try cleaning the slider. Be careful though, it is extremely delicate and requires one of those tamperproof Torx keys to remove it.
 
  #10  
Old 02-12-2019, 10:23 AM
Weekend Warrior
Join Date: Feb 2019
Posts: 10
Default

interesting thread, I had the same problem
 

Thread Tools
Search this Thread
Quick Reply: Honda TRX 420 ES cold start problem


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: