2010 mod- Wife's ATV-. She is disabled- rides it with little throttle - its never been abused- used on flat ground-regular servicing. It ran well for years- Now engine just stops- . Engine cranks- but will not fire. No spark- and fuel pump makes no noise when ignition switched on. Wait 10 mins or so- and it will start.?. Dealer replaced oil press sensor- but problem persists. Dealer unable to find fault - says to bring it in when it stops- but it only goes dead for 10-20 minutes or so. Infuriating. dam thing just stops- so wife has to sit on it waiting for the magic start time to pass before it will fire again. Power steer issues also- has stopped working- PS light does not extinguish when engine is started- replaced PS ECU- made no difference- suspect PS motor is US - so wife uses it without PS. Any thoughts among you quite brilliant analysists - Will be most anxious to read any thoughts .

 

Someone I know is having the same problems with a new 420 auto, still under warranty so dealership is trying to fix it. Apparently the reverse sensor at the back of the engine can be suspect, they tried tightening the connector on it with no result so have fitted a new sensor, no result, and have now fitted a new bit of loom between switch and main loom. It did the none starting trick on me a few days ago, (before the new bits) and fault coded 6, 1 on the gearchange display. Does your gearchange display or engine warning light flash a code (in Morse) when the fault is on?

A problem I have come across on non Auto old model 420s is the fuel pump relay in the battery box going wrong, not sure if the Auto has the same set up. also fuel pumps can get a bit intermittent, sometimes working sometimes not, when switched on, but I expect it would still spark. On 420s I think the starter still works with the kill switch on kill, could it be a faulty kill switch?

 

Hi Merryman- many thanks for your thoughts- this issue driving me nuts- my wife (kay) just patiently sits it out until it starts again and she can get in from the orchard- as she is disabled and not able to get off it and walk back to the house. There is a slight problem- I cant convince my wife to look for "error codes" - she is 61- and although she was a fearsome female endurance rider years ago (Finke desert race and as a sponsored by Honda Australian safari- first female ever to finish) - to her it's just a flashing light.

It has never failed whilst going backwards- so can that sensor still be an issue.

Kill switch not the problem- we never use it- remains on- always use the ignition. On this 420- the engine always cranks despite there being no spark.

Both dealer (who relies on error codes) and myself have checked the fuel pump - all ok- good pressure of fuel out the hose.

She always just "potters along" - 3-4 mph and it stops. When in dead mode- the engine cranks- but no whirr sound of the fuel pump activating when the ign is switched on.

The Honda dealer tunes race bikes- so he is no slouch- but immediately looks for error codes by triggering the ECU-. I merely have some past experience- OH- for the good old days with 2 stroke race bikes- if there is fuel-air and spark- it will go. The dealer says it has very and needlessly complicated circuitry- and the problem has never occurred for him when it has been in for a service- and when it does occur- I cant get it into him before the "rest" period where it just restarts again.

My thought was to just start replacing in an organized sequence- every component which when it fails has the capacity to kill the spark- but he says- not as easy as that - could be replacing parts for ever and not finding the one with the intermittent fault- I hate these words- "intermittent fault and dry IC joint"..

The EPower Steer has failed- light remains on- have replaced the EPS - Computer CU- no change- but figured no sense throwing good money after bad - Kay can use comfortably it without the EPS- so we are trying to solve the Engine out issue first.I can't even sell it knowing it has a major fault- its a very small community here and I do not need to deceive someone. about this machine..

I really do appreciate your input- maybe I just wait until it occurs again- and if I am within 100 yards- shuffler over (cos I am 72) and record the ignition error flashes - then repost again?
Kind Regards Danny K… PS sorry post is so long- its been a real pain for years
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I am with the dealer about the needlessly complex circuitry. Honda use two positives fed from battery through ignition switch right from the 300 model. On some 420s after the ignition switch, they have one of these positives feeding a relay which switches the other pos wire on, why? I can see no logical reason for this, but have had a few where the wire that switches the relay has corroded so nothing works, trick the relay and everything works. All the rest of the ATV industry use a belt drive variator for autos, dead simple no electronics, and much smoother than the awful notchy electronically controlled manual gearbox of the 420 auto.

Best thing you can do is use the bike yourself for a while, when the fault comes on you can then read the code if it throws one. Another moan here, when they introduced fault codes, having it in Morse made some sense, but with the digital dash, they could now, like Suzuki, simply have the code come up as a number on the display, the flashing codes are difficult to read, especially as they get more complex. Your dealer should be able to retrieve old codes after the fault has gone away though.

That you never use the kill switch does not alter the fact that it may be this circuit that is faulty, the wires to all the handlebar switches move with the steering so can simply fatigue fail. Anyone who has had a 300 Fourtrax for any length of time will have had this on the main ignition wires to or from ignition switch.

 

I maybe guilty of over thinking something here- I tried the kill switch- turned it off- with IGn Sw ON- neutral green light and Amber PS light remain on- Engine WILL NOT crank... Turn Kill Sw back on- and relay clicks under seat and Fuel pump "whirrs"- AND ENGINE WILL CRANK AND FIRE. Does this test indicate there is no issue with the Kill Sw wiring loom-because engine still cranks .?.
When the intermittent fault occurs - generally at low engine revs- the engine dies- BUT WILL STILL CRANK. . On several occasions the fault lasted long enough to check the spark lead and coil- no spark. The fault is intermittent- up to maybe once a week- it lasts only 5-10 minutes- and the quad is ridden daily- minimum of 1 hr- sometimes a lot more- its the only means of getting about out doors for my wife..
Last year dealer extracted error codes for EPS - 14,18,21 which he said were all voltage/current related- So- new Voltage reg- battery was new- so checked for voltage and Amp capacity- all OK- cleaned batt connections- replaced oil press sw in case it was low oil press killing the engine. This did not fix the power steer issues- it still does not deliver power steering assistance- the PS light remains on at all times-despite aa new EPS ECU but it did seem to resolve the intermittent death of the engine. It seemed OK for a few months- then it has started again.
I am getting a bit confused- I dont recall any error codes blinking (the engine display light) last time the engine died a few days ago.
Is it possible there is an OIL PUMP regulator failing to maintain oil pressure and causing the engine to die. Its something which after 10 minutes rights itself - until the next time which might be several days or a week. The dealer who rides test track said there is a bank angle sw like on race bikes to kill the engine in event of a spill- but that could not be the problem because the quad potters around on flat ground. What ever it is - is annoying the hell out of me- wish I had kept the old Blue Yammy Kodiak- with sequential belt drive transmission- it had 4wd-I only got the Honda because of Power steer assistance for my wife - and that was the first to fail- SHEEEESH..
Any thoughts appreciated - as I have run out of cogent options..

 

"I tried the kill switch- turned it off- with IGn Sw ON- neutral green light and Amber PS light remain on- Engine WILL NOT crank".
Sorry, must be the new model 420 that still turns over on the starter with switch in the kill position, it fooled me for a while the first time I unknowingly knocked it and the bike turned over but wouldn't fire.

The dealership should be able to trace the EPS fault fairly easily, We have never had an EPS fail, except a 750 Suzuki that turned out to be rats eaten the wires to the ECU, easily fixed except they had chewed them off flush with the aluminium ECU case, had to open it and found bits of wire still connected to plastic ECU inside. ECU warning light should flash a code, just like EFI warning light for fuel injection, or geachange display for gearchange faults. I suspect a faulty EPS motor would show up as a fault as the resistance in the wires from the motor would be checked by the ECU. The system may not be sophisticated enough to do that though.

I can't see a low oil pressure sensor stopping the engine, as the engine has to start with no oil pressure, not even sure it has one, few ATVs do, oil temp, yes. About all you can do is give the bike to the dealer, ask for a courtesy bike and tell them to keep your machine until they get it right. We are lucky as the boss also has a farm and can use customers bikes until the fault comes on, in the case of intermittent faults.

 

Your thoughts on this most appreciated. I will print them out and take them with the quad to the dealer this week. The Quad stopped again tonight (as my wife was out looking for our 2 collie (sheep)dogs- but we got no sheep for them to bother so they chased a hare across the neighbours fields- off into the sunset- the hare won - but back to the quad- I had asked Kay to particularly look for flashing engine light- she said the quad stopped while she was going about 6kph- she switched it off and on- but there was no flashing light- only the gear indicator which she put back into neutral and it started after a few minutes.
I will ask him to particularly examine and test the kill switch loom integrity for rat chewing (we do have them here also) and put his mind to the conundrum - why or what component causes spark to die in connection with some other issue- yet seemingly resets itself after a short period and allows the quad to fire when cranked.
I will advise you by this post- or maybe post direct to you- any thoughts or successes in the matter..
I dont hold out much hope- but thanks again for your time and effort.- Danny & kay.

 

I’m having the same problem and it’s driving me crazy. Have you found a solution yet? I would greatly appreciate your feedback.

 

PROBLEM SOLVED. The issue IS the fuelpump relay- Located behind/under the seat.near the tail light. tests Ok - when cold- Throw it out and put a new one in- v.small cost- Your 420 Quad will run like new. OK- How did I discover this- I have a real smart mechanic/honda dealer- he went through the parts orders for lots of dealers to find what part was UNUSUALLY being purchased that might be the problem- he found more relays being purchased - he thought this was unusual. So he told me. problem solved- no issues in 6 months. NOW- who knows how to solve power steer failure issues- The dealer says just replace the whole lot - Computer unit and power unit- wish I had his access to cheap parts. performing the chip reset indicates it should reset- but No- so I have given up- use it with no power steer. Now the gears jump from 2nd- to 4th. Might be time to get rid if it. best Danny K.

 

Wow, only 3 years ago and I didn't know the answer, since then I must have had over a dozen old model 420s with this problem. Fit a new relay and away they go. Another trick the relays play is to stop the bike charging. Fit a new voltage reg and you find it still doesn't charge, so you assume it must be the stator, which is an absolute swine to remove on an old model 420 (book says take the engine out). However, it is quite often one of those relays in the battery box, how they can stop it charging is a mystery, but they can and do. Recently I seem to have been using loads of those relays, even have the bit of loom with two new relays dangling, so I can plug it in and see if that fixes a bike with the aforementioned faults, I have had trouble with that bit of loom too, permanently in sludge, unless you do the dealer mod of fitting a sheet of plastic over the battery and, of course, just where rats and mice go to get at spilled grain.