CRF 450 2014 won't idle

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2/21/2019 5:11 PM

Picked up the bike cheap, would only start with high idle pulled out, if high idle is turned off but you keep the revs up it will run.
Checked the TPS, it was at 0.469. I tried 0.5 and 0.55 without improvement
Replaced the very dirty fuel filter with new
Checked valve clearances
Removed 300ml of gas from the oil!!!!! (not sure how long it was there for?!)

Today after being started/dying 10-15 times the plug fouled, I cleaned it up and it began sparking again but it doesn't seem the best - not sure if a bad plug would cause the idling fault though? Can't get my hands on a plug until Monday.

TPS now sits at 0.5, from cold I can pull the high idle it will idle and then I turn the high idle off and it will idle for around 15 seconds before dying, it will kick first time most times but just refuses to idle. Also if you open the bike right up, let off the throttle and then give it gas again it seems around 30% of the throttle opening doesn't respond almost like it's starved of fuel but once you let the bike catch up then it works as expected. I have attached a video below of how the bike starts/idles.

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2/21/2019 5:33 PM

Fuel pump or screen attached to the pump?
If you cleaned the dirty screen on the fuel pump it probably has debris in the pump or line.
Seen that stall before, fuel starvation.
Crazy how inexpensive the aftermarket pump and screen is.

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2/21/2019 6:34 PM
Edited Date/Time: 2/21/2019 6:35 PM

The fuel in the oil concerns me; as well as the plug fouling leads me to believe you might have an overly rich condition... possibly a leaking/ hanging injector... The fast idle circuit opens an air passage so you’re actually leaning the system out when it’s pulled...

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2/21/2019 6:41 PM

Paul_Pitzonka wrote:

The fuel in the oil concerns me; as well as the plug fouling leads me to believe you might have an overly rich condition... possibly a leaking/ hanging injector... The fast idle circuit opens an air passage so you’re actually leaning the system out when it’s pulled...

I think the fuel in the oil is a common CRF problem, especially given the bike has had this problem for 6 months with the previous owner and he spent countless hours trying to diagnose it, I will be checking the oil again tomorrow though to see if the problem persists.

By it being overly rich are you suggesting it is getting too much fuel? It's difficult because from what I can see Honda do not provide a TPS specification and from what I read online people recommend 0.50 - 0.56 for the TPS setting, at 0.50 it means I am giving it less fuel compared to 0.56?

Interesting, when the high idle is pulled it opens an air passage and then that results in more fuel being sucked through or what? I always thought on the EFI bikes the high idle meant it dumped more fuel in.

The pump seems strong however I have a fuel tank + pump from an RMZ 250 2012 here that I could possibly hook up and see if that makes a difference?

What do you guys make of the video?

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2/21/2019 6:41 PM

speed_racer wrote:

Fuel pump or screen attached to the pump?
If you cleaned the dirty screen on the fuel pump it probably has debris in the pump or line.
Seen that stall before, fuel starvation.
Crazy how inexpensive the aftermarket pump and screen is.

Hey! I didn't see a screen attached to the pump, I replaced the fuel filter itself.

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2/21/2019 7:01 PM
Edited Date/Time: 2/21/2019 7:12 PM

Paul_Pitzonka wrote:

The fuel in the oil concerns me; as well as the plug fouling leads me to believe you might have an overly rich condition... possibly a leaking/ hanging injector... The fast idle circuit opens an air passage so you’re actually leaning the system out when it’s pulled...

munch wrote:

I think the fuel in the oil is a common CRF problem, especially given the bike has had this problem for 6 months with the previous owner and he spent countless hours trying to diagnose it, I will be checking the oil again tomorrow though to see if the problem persists.

By it being overly rich are you suggesting it is getting too much fuel? It's difficult because from what I can see Honda do not provide a TPS specification and from what I read online people recommend 0.50 - 0.56 for the TPS setting, at 0.50 it means I am giving it less fuel compared to 0.56?

Interesting, when the high idle is pulled it opens an air passage and then that results in more fuel being sucked through or what? I always thought on the EFI bikes the high idle meant it dumped more fuel in.

The pump seems strong however I have a fuel tank + pump from an RMZ 250 2012 here that I could possibly hook up and see if that makes a difference?

What do you guys make of the video?

I’ve done quite a few of the modern crfs haven’t seen one with that much fuel wash... (doesn’t mean it isn’t a common problem)... yes, .50 is leaner opposed to .56... most of the bikes seem to respond well to a range of .58-.62... however I just had a 2018 crf that ran better at .52... and if you look at the throttle body when the plunger is pulled it opens up a bypass circuit around the butterfly... I don’t think it results in more fuel being pulled as that is mainly controlled by the injector spray... id still check for a dirty/ hanging injector... As long as your TPS is close the bike will run, I highly doubt tps setting is your issue (although still a great idea to dial it in once you have the bike running correctly)...

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2/21/2019 7:09 PM

Try TPS setting of .62 volt at idle.
A leaking fuel injector will cause the fuel in oil issue. It will also cause the bad idle issue.
Low fuel pressure from faulty fuel pump will also cause idle issue.
Also you can adjust the idle speed up to see if that helps.

Paw Paw

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2/22/2019 8:15 AM
Edited Date/Time: 2/22/2019 8:16 AM

Does anyone know why my TPS unit would now be reading 4.5v???! I am using the same power source as before that still reads 5v.

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2/22/2019 8:26 AM

Is the 5v at closed throttle?
Your 4.5 volt reading at the same spot?
If at closed throttle, then the TPS is bad and would be allowing too much fuel to be sprayed by the injector.
Remember that the lower the voltage (IE .62 v) reduces the fuel delivered and the higher voltage (IE 5v) is for max fuel delivery. .62v should be at closed throttle and 5v should be at WOT.

Paw Paw

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2/22/2019 10:08 AM

Paw Paw 271 wrote:

Is the 5v at closed throttle?
Your 4.5 volt reading at the same spot?
If at closed throttle, then the TPS is bad and would be allowing too much fuel to be sprayed by the injector.
Remember that the lower the voltage (IE .62 v) reduces the fuel delivered and the higher voltage (IE 5v) is for max fuel delivery. .62v should be at closed throttle and 5v should be at WOT.

Paw Paw

My wires weren't touching the TPS terminals properly, sorted that and set it to around .625 and it now idles!!!!

The bike now starts and idles however it still isn't being fueled properly, if I open the throttle slowly and close it slowly it is fine however if I WOT quickly then close throttle and open it again for 1/4 of the throttle nothing happens it's like dead, like it is running lean(??). I am wondering if this is caused by running the bike without seat/plastics maybe it's getting too much air?

Is it normal to go above the .62 or is it the most I should go? It doesn't back fire at all so doesn't seem to be over fueling

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2/22/2019 10:18 AM

.62 should be correct.
Back fireing is normally from a lean condition.
Clean you injector.

Paw Paw

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2/22/2019 10:22 AM

Paw Paw 271 wrote:

.62 should be correct.
Back fireing is normally from a lean condition.
Clean you injector.

Paw Paw

How do you recommend I clean the injector? I hooked it up to a 9v battery and blew some carb cleaner through and soaked it for a while in carb cleaner already.

Is it worth putting some fresh gas in with some sort of injector cleaning and running it through?

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2/22/2019 11:15 AM
Edited Date/Time: 2/22/2019 11:17 AM

Paw Paw 271 wrote:

.62 should be correct.
Back fireing is normally from a lean condition.
Clean you injector.

Paw Paw

munch wrote:

How do you recommend I clean the injector? I hooked it up to a 9v battery and blew some carb cleaner through and soaked it for a while in carb cleaner already.

Is it worth putting some fresh gas in with some sort of injector cleaning and running it through?

Have you checked fuel pressure when the bike is running? also how does the spray pattern look on the injector?

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2/22/2019 1:54 PM

Paw Paw 271 wrote:

.62 should be correct.
Back fireing is normally from a lean condition.
Clean you injector.

Paw Paw

munch wrote:

How do you recommend I clean the injector? I hooked it up to a 9v battery and blew some carb cleaner through and soaked it for a while in carb cleaner already.

Is it worth putting some fresh gas in with some sort of injector cleaning and running it through?

Paul_Pitzonka wrote:

Have you checked fuel pressure when the bike is running? also how does the spray pattern look on the injector?

I don't have the tools to check the fuel pressure unfortunately, I did look at the spray pattern, not really sure what good looks like but it looks OK to me? I can try to record it tomorrow maybe.

I have access to a fuel tank (+pump) from a rmz 250 2012, I could hook that up to the bike and see if that helps but I'm wondering if the 250 has a less powerful pump?

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2/23/2019 2:51 AM

It seems I locked the topic by accident it is unlocked now laughing

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2/24/2019 2:59 PM
Edited Date/Time: 2/24/2019 2:59 PM

Today as I was out of ideas I had a lot more time on the bike just testing around the yard. Some things I found:

If I go from 10% throttle > 100% it pulls like a train, perfectly fine

If I go from 100% throttle > 0% then around 30% of the throttle is totally unresponsive, almost like I'm not actually opening the throttle then suddenly it will catch up and the throttle will do something.

If I hold revs at around 40% and ride like that then it will start to run weird, jerky and will pop and just not run correctly.

After riding it up and down the yard a few times I rode it a little with the high idle out and it felt no difference at all however I opened the bike up with high idle ON and once I came to a stop the bike died, turned off high idle and it was a bit more difficult to start now compared to before. Since then the bike has ran similar to how it did before I reset the TPS. It really feels like the TPS has moved from 0.62 to 0.55 or something but the bolts are very tight but I will double check it.

Below is a video to show how it was running at the end of the test. It would now take a few kicks to start, sometimes it would idle and sometimes it would just die. When it was revved it was running pretty badly.




So currently the TPS should be set at 0.62 (will double check it hasn't somehow changed tomorrow)

I have tested a different fuel tank + pump on the bike from a different bike and it ran the same. (rmz 250 2012)

Anyone out there have any idea? I am starting to run out of ideas now. The only thing I haven't done is properly had the injector cleaned, I am tempted to grab 1L of fresh fuel and mix in some sort of cleaning solution. Is that usually effective on these systems?
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