Hi All,

First of all I have been a member of this site for some time but thought it is best to read all the posts rather than ask the same question and annoy people but it looks like my problem is different than the ones about the FPR.

I have a 2004 CBR600F4i and I am pretty unhappy with the mpg figures. All I can get is around 90-100 miles until the reserve light comes on.
I read a lot of posts ( literally every post about F4i and fuel issues), and most of the posts here seemed to be related to FPR ( Fuel Pressure Reg) and I decided to replace it.
After replacing this week, there is absolutely no difference to the consumption.
I decided to check the exhaust and held my hand close to the exit of the exhaust pipe and noticed unburnt petrol is spraying out of the exhaust pipe, especially if I open the throttle!

So before you say spark plugs, I must say bike is at 34000 miles and plugs were changed at 28000. Oil changed recently about 1000 miles ago, I checked map sensor and vacuum hose, seemed to be correctly connected, checked air filter( was clean), checked the sensor on top of the airbox( disconnected and ECU gave a fault light so must be working right)...

I am not sure what else might be causing this but I am running out of ideas, and smell of unburnt petrol is noticeable when I first start the bike.

Performance-wise, there are no symptoms, it runs fine, idles normal, does not stall or knock, just consumes hell of a lot petrol.

People seem to be getting 150 miles per tank and me getting only 90 is just annoying, especially if I cannot pinpoint what might be the issue.

About the bike, it has a full Delkevic exhaust pipe on it, but it already had it when I bought it and did not have such poor mileage at that time. Other than that, only different part is K&N air filter but I do not think that is the issue.

If you could help me, I would be very grateful as I am stuck at the moment and do not want to take it to a garage since they dont seem to have a clue either.

 

Fuel pressure regulator.......

 

I have already said that I changed it, so not that.

 

Did you take the plug off before installing it? Seen it done....

You might have an injector leaking.

 

Yes I removed it. Someone told me it might be spark plugs.. Would ecu dump more fuel in the piston to compensate for mistiming spark plugs? Because i didn't notice any performance drop its just very low mpg im getting along with smell of raw petrol.

 

How far are your avg rides? Do you commute?

 

Yes I commute a rather short distance of 5 miles one way everyday.

 

He already said the bike didn't have this mileage in the beggining, meaning something has broken on the bike.
Since you already replaced the FPR, I'd be looking into the injectors themselves and see if one is sticking open too much. Ignition would have nothing to do with un-burned fuel making it out the exhaust. You said full exhaust and then you added a k&n- was the bike ever tuned for these mods? Could be part or all of the problem there. I know the k&n for F4i's sucks as it does not have the airflow managment flaps built in like oem, hence why I never installed the one I bought long ago.

 

Not true, miles per tank doesn't paint the full picture. Especially if there are no other symptoms.


If you're letting the bike warm up before taking off, that mileage will happen. Happened to me in college - I was solely commuting for a few weeks and only getting around 90 before the light came on.

No other symptoms. Bike ran fine. Mileage doesn't account for the few minutes the engine's burning fuel while its on the sidestand.





But you did say you smell "raw petrol". Pull the plugs and look at them. They'll be very wet of you're running really rich.

 

Yeah i let it warm up until 60 C ( cant tell what it is in fahrenheit but choke stops at that point).

The only real symptom is low mpg and smell of petrol but that being said it only smells like that early in the morning when i fire it up from cold. Black soot in exhaust too. I could take photos if that helps.