Please help???!!! My son was riding his 03 CBR600RR and out of nowhere it decided to start running like it only has three cylinders. There are no codes and all plugs have spark so we are leaning toward a clogged ejector etc. The bike cranks every time, but it runs just out of tune so to speak. No power! Classic fowled plug syndrome but everything electrical checks out fine. Fuel pressure regulator?? There is no fuel filter that I can find.

Any help would be very appreciated!

 

is more than one plug fouled if its the fuel pressure regulator its usually plugs 2 & 3 and will fill up with gas in those cylinders you can pull the vacuum line on the regulator with the key on to pressure the fuel system if fuel drips out of the regulator then its bad

 

Thanks for replying so quickly. I checked out the bike and I was unable to identify the pressure regulator. I have seen pictures of a unit off of an F4i...it's supposed to be bell shaped and located near the air box right?. I assume an 03 has one. I can't emphasize enough how well the bike cranks and seems to want to run normally, but just can't seem to sink. Since the plugs all fire it, seems like the fuel system is the way to go, but I am a firm believer that when you have to pull out a manual, put it down again and go check the easy stuff.

 

Have you tried ohming the injectors?Another thing to try is to get a hold of an engine stethoscope and listen to each injector to see if they are all pulsing.

 

Yep! Ohmed out all ejectors and checked the connectors for voltage and all are within specs. Haven't tried the tried the old ultrasonic screwdriver trick but what the heck may as well. I noticed a lot of posts concerning this year and relay/rectifier issues, but everything appears to be ok electrically and there are no issues with starting. Any thoughts?

 

Did you check the plugs themselves, or just the wires to see if they are getting spark? You may need to start digging deeper like running compression tests and leak-down, but I would also be sure to check the fuel pressure regulator as stated before.

 

Yes, we replaced the plugs and checked the spark on each one. As far as the fuel pressure regulator, can you describe where it is located on an 2003? I sure hoe it isn't compression, but you may be right...

 

I am not sure. I was checking my manual, but I have a modular fuel pump unit with the regulator built in. You may check the fuel rail, or right under the tank. Look for a vacuum line connected to it. Maybe one of the early CBR guys will step in here and help with the location. Personally, I would think it would crank for a while before starting and then run rich if the regulator was bad.

 

That's what makes this so strange, it cranks right up! No mess, no fuss. Even when it's running everything is almost normal, but the power is just not there . Like I said, very similar to when a bike has a bad plug wire etc. Didn't get time to mess with it last night but tonight I will keep delving and keep you posted. Thanks for the thoughts though and I will be on the look out for the regulator.

 

Just thought I would tell you. By utilizing an infrared thermometer and swapping around coils I was able to get all four cylinders firing. #4 being the offending cylinder, but I was also able to verify that the #4 cylinder is significantly cooler than the other three by about 100 degrees. Could this still be a firing problem even though the issue stayed with the cylinder and didn't follow the coil when switched?

The other possibility being compression and a possible head gasket problem, but we have seen no decrease of fluid in the radiator tank.

Any thoughts?