Yeah it doesnt have one. I didnt remember ever seeing one on a fuel injected bike.

 

I just talked to the guy that went to mmi. He said he knows he checked the fuel psi right. So could the bike even function properly like this, with ~14 psi? I wouldnt think so... Maybe his gauge is off.....

 

Correction. he said 38 psi. So would it even run as good as it does off 38?

 

Did he mention how he measured the pressue? If he measured after the fpr does its job, the the pressure will be less than 48-50 psi the pump is required to pump. the pump itself should put out the 48-50, but the injectors are probably only using the regulated 38 psi. So it depends on what he measured and where. He may be correct. If the injectors are requiring 48-50 psi, and your only seeing 38psi, either the pump or the fpr is failing.

As for if it would run or not on 38psi. Again, it all depends on the range the injectors are rated for. In all honesty, injectors don't kind of work. They either have enough pressure to open and spray the gas, or they don't. So if your pressure is dropping below what the injectors require to work, the bike would simply die, not just idle low, which makes me think tps or temp sensor.

On the throttle position sensor, you should be able to unplug it, measure the resistance at no throttle input, then again at full throttle to see where the resistance is. If its within range, its not the problem. Sorry, I don't know what the specs are. But an ohm meter is what you will need to use. If I had to guess, your current setting on the tps is on the edge of being within the idle range.

As for the temp sensor. I've never tested one, but I believe there is the same basic resistance check for it as well. There should be a range of resistance for it to fall in at certain temps.

Hopefully you know someone who get you the proper specs to test those items with.

On the petcock, I don't know about the F4i's, but my wifes fuel injected 636 had one. However, it wasnt the same as carbed bikes. It was actually under the tank, basically just an on/off switch for removing the tank. If your bike has one, make sure its open all the way.

You've probably already been there, but make sure your fuel line is routed correctly and not kinking at all.

Do you have air box mods beside the removal of the air tubes? And this is a long shot, but sometimes, the removal of the air tubes can create disturbances within the air box that normally wouldn't be there. The tubes can smooth out the air flow, when removed, the air just tumbles around in the box. I don't know that it would affect anything on that type of injection where the injector is bolted directly on the throttle body, but it does make a difference on certain models with the injectors set apart from the throttle bodies. Again, probably not the issue, but just something to consider.

 

How is your voltage? Do you have a good ground? Reason I ask is you say you rev it a few times and it goes back to normal, but if at idle it will start to fall. Voltage may be dropping low enough to cause the pump to loose pressure.
I myself would check grounds and then the voltage regulator. Just my .02

 

The low idle and then rev to correct only happened once. I seriously doubt thats the issue. And yeah all the grounds are good.

 

[quote=justasquid;954768]Did he mention how he measured the pressue? If he measured after the fpr does its job, the the pressure will be less than 48-50 psi the pump is required to pump. the pump itself should put out the 48-50, but the injectors are probably only using the regulated 38 psi. So it depends on what he measured and where. He may be correct. If the injectors are requiring 48-50 psi, and your only seeing 38psi, either the pump or the fpr is failing.

Idk where he checked it from but im gonna recheck it myself this week. If I wanted to check after the fpr, how would I go about this? Its on the fuel rail. What do I remove to check from the rail? Also I think I read they are 50psi injectors some where, but that doesnt mean they are suppose to run max psi..... im guessing.

As for if it would run or not on 38psi. Again, it all depends on the range the injectors are rated for. In all honesty, injectors don't kind of work. They either have enough pressure to open and spray the gas, or they don't. So if your pressure is dropping below what the injectors require to work, the bike would simply die, not just idle low, which makes me think tps or temp sensor.

I agree, where is the temp sensor to check it?

On the throttle position sensor, you should be able to unplug it, measure the resistance at no throttle input, then again at full throttle to see where the resistance is. If its within range, its not the problem. Sorry, I don't know what the specs are. But an ohm meter is what you will need to use. If I had to guess, your current setting on the tps is on the edge of being within the idle range.

Got a question, does the bike have to be running to check wot ohms? Do you know where I can find the correct specs?

As for the temp sensor. I've never tested one, but I believe there is the same basic resistance check for it as well. There should be a range of resistance for it to fall in at certain temps.

Hopefully you know someone who get you the proper specs to test those items with.

On the petcock, I don't know about the F4i's, but my wifes fuel injected 636 had one. However, it wasnt the same as carbed bikes. It was actually under the tank, basically just an on/off switch for removing the tank. If your bike has one, make sure its open all the way.

You've probably already been there, but make sure your fuel line is routed correctly and not kinking at all.

Yeah its correct.

Do you have air box mods beside the removal of the air tubes? And this is a long shot, but sometimes, the removal of the air tubes can create disturbances within the air box that normally wouldn't be there. The tubes can smooth out the air flow, when removed, the air just tumbles around in the box. I don't know that it would affect anything on that type of injection where the injector is bolted directly on the throttle body, but it does make a difference on certain models with the injectors set apart from the throttle bodies. Again, probably not the issue, but just something to consider.

No, but people stunt most bikes without air tubes, even on f4i. A friend of mine rode a season without them on his f4i and all was great.




If anyone can find me the correct specs on fuel psi after fpr, correct ohms of the tps sensor and the temp sensor, it'd would be awesome! And I would deeply appreciate it.

 

Oh well, I tried. Good luck and keep us posted with more symptoms. Where are you located? If in SoCal you can stop by our shop and we can get a better idea of what is going on.

 

Im in Mississippi. Idk what im gonna do about this.... No one is willing to figure out this problem and I dont have the tools at home to check anything electrical.

 

If you have a pdf reader, you can go here and download the service manual which will have all of the specs you will need.

http://downloads.hondatech.info/Moto...e%20Manual.pdf

You can then save a copy to your computer. It does take quite a long time for it to load, at least it does for my computer, around 3 minutes, where all there is a white screen, but it does load. If it doesn't load for you, I downloaded it just to have it and can email it to you if it doesnt open for you.

regarding your tools, multi-meters have become extremely inexpensive. You can pick up a decent digital multi-meter for less than 30 bucks. Try your local autoparts store or even places like walmart have ones accurate enough to diagnosis most electrical problems.