So I have a 2007 Honda Rancher 420 ES ... Fuel Injected ... and I'm at my wits end with it. She has about 3k miles on it now (341-hrs). When I got it, I had to do a top-end rebuild - so the compression is great and anything in that area is tip-top.

Issue I'm having is the ATV seems to run rich - like a gas smell from the exhaust - even though its EFI. Also, it'll run fine for about 10-15mins ... then, it'll bog down & cut off. It'll not restart until after it sits for a bit (10-mins or so). The exhaust smell is "my perception" & may be typical ... but the cutting off is definitely not and is my primary concern.

Thing's I've did so far:
- New HONDA 16700-HP5-602 Fuel Pump (replaced twice)
- New HONDA 16950-HP5-601 Petcock assembly
- "Complete" new HONDA 16400-HP5-605 throttle body assembly
- Complete clean of the fuel system
- New HONDA 38580-HP5-601 RELAY

Anyone else had the same experience & could possibly offer suggestions? I've searched & see several posts on the web with the same exact symptoms (less the perceived smell) - but, I never see a "fix".

 

Does atv have any code blinking on meter?

 

None whatsoever.

 

Is the spark plug black and sooty when the fault is on? The EFI system relies on the sensors to tell it how much fuel to inject. Just possible that the engine temp sensor is telling it that it is at -20 degrees all the time, so on full choke. This wouldn't throw a fault code. Other possibilities are conventional ignition problems, faulty plug, or coil, or pickup coil on flywheel, but I know Suzuki EFIs fault code if the spark is lost, so expect Hondas would do too. I assume you changed the injector along with the throttle body?

I have had quite a few old model 420s which cut off after 15min or so but that was always either a blocked fuel filter or one of the relays in the battery box, and you seem to have changed these, though if you have only changed one relay, it could be the other. One relay puts a -- up on the gearchange indicator when the fault is on, even on manual change models.

 

Honestly, I haven't pulled the plug yet ... it was new when I did the top-end rebuild & it never really crossed my mind to give it a look-see. I'll pull it for inspection.

Guess I'll throw some more $$$ at it too and replace these components:
- ECT Sensor (37870-HN8-A60)
- IAT Sensor (37880-MCA-003)
- Ignition Coil (30510-HP5-601 & 30700-MBN-671)

If no joy, she may be finding a new home. I don't know what else to check!

 

Any codes blinking going on Have IAT and coil to be common here no code I would do coil first

 

As you haven't changed the plug, the first thing is to do so. A new plug doesn't always equal a good one. Another thing I forgot to mention is the voltage at the battery with engine running. A faulty voltage regulator can throw weird faults on the EFI system, though as over, and under, voltage readings on some sensors is detected by the ECU, and this throws a fault code, I would have expected a code to pop up.

Frankly, once you get to substitution rather than checks, it is often cheaper to let the dealer have it. They know the regular faults and, worst case scenario, if they need to fix by substitution, they can pull a spare of the shelf and, if it doesn't fix the problem, take it off again and put it back in the stores, so do not need to spend on parts that don't fix it.

 

Spark plug tells me what I was smelling ... engine is running rich "for some reason".

 

Well, I replaced the following components:
- Spark Plug (NGK BKR5E-11)
- Ignition Coil (30510-HP5-601)
- Spark Plug Boot (30700-MBN-671)
- Engine Coolant Temp (ECT) Sensor (37870-HN8-A61)
- Intake Air Temperature (IAT) Sensor (37880-MCA-003)

I also did the TP Sensor Reset Procedure that I should've did when I replaced the throttle body assembly.

So far, so good ... exhaust didn't seem to smell as rich as it did before too. Maybe I sorted it?

 

Sorry, I forgot to mention the TPS reset procedure, strange ritual isn't it. I would have fitted one new bit at a time to ensure I knew exactly what fixed it but, as it seems to be fixed, hope you have many hours of happy riding, just keep the rear hubs, and those big nuts beside the diff, tight. I hardly ever service an old model 420 where one of them hasn't come loose.