Hello, I'm new to the forum. Sorry, this post will be long but very detailed. My sons 96 cbr 600 has been running outstanding for 2 months now (since he purchased it). Last week it started to have a stumble or what felt like fuel starvation at cruise or when you jumped on the throttle. Two more tanks of gas at two differnt stations and it has gotten to the point that it acts like the fuel valve is in the off position and the bike is starving, then just before it dies it gets its fuel back and off it goes again for another mile and we start all over. So I have replaced the 17 dollar fuel filter, I have tested the pump on and off the bike. The pump operates on a 12 volt power source on the bench forever. On the bike it operates and after it pressurizes it goes to the 1 pulse every 5 seconds. so it appears to be normal yet when the bike starts to die i reach down and the pump isnt operating untill the bike almost dies then it starts pumping again the bike stumbles and catches and goes again. No mind you it will start and idle all day long and never miss a beat. I believe the pump has a weak internal pressure regulator that is sticking and siezing the pump long enough to cause the bike to almost die then it goes oh **** I need fuel and the pump tries to play catch up. I dont believe it to be the fuel relay cutoff to be intermittent or the cdi because to me if it was that it wouldnt die everytime like clockwork. So i am purchasing the pump, however bike parts are ridiculasly expensive and a man can go broke throwing parts at these machines so if anyone else has a differnt idea of what is wrong PLEASE LET ME KNOW. I am looking for a person who has dealt with this issue or very close to it. I am trying to help my son and get him back on the road with minimal drama.
thanks
Tom

 

The Fuel Pump is most likely the way to go. RonAyers.com will probably have the best price. Or ServiceHonda. I've had the same problems you're experiencing.

 

fuel pump.

when i was messing around with my cbr like 2 days ago (fixing some idle problems too), i forgot to hook up my fuel pump. guess what, i got the same symptoms. like yours, it idled but hesitated or died when the throttle is twisted. try changing the fuel pump or feel it when you press on start. the pump should feel kind of fast.

 

Thanks, like i stated, The pump is pulsing and operates fast when first activated. i just believe that it gets stuck and when the bike starts to die and the presurre drops then the pump realize oh crap i need to turn on again, by that time its to late and the bike dies or almost dies untill the pump repressuirezes and engine recovers. Im going to check a few things tomorrow and then look for a damn pump, just hate to spend the 150.00 and that not be the problem..

 

You can by pass the pump & see if it still has the same problems. The F2's don't have one, not saying disconnect permanently, just to confirm your diagnostic.

 

Can you run a fuel line into the pump on the bench to let it pressurize and see what happens? Try to narrow down all those variables. Also, do Pacemakers idea and run a line straight to the carb.

Whatever it ends up being, don't buy the part from wherever you got that filter from, as you paid far too much: http://www.shopwizardscycle.com/inde...PROD&ProdID=97

 

I figured it out, All I need to do was come to work and get away from the wrenches for a while and the kid standing over me asking when would his bike be ready to ride again LOL. So what was the apparent problem:

I read about the direct air intake on the forum and how important the proper air pressure verses fuel is on the cbr. So today i inspected The D.A.I and found nothing wrong but I found the aircleaner was clogged more than I have ever seen. So sent the boy to get a K&N filter and four new plugs. Low and behold she's screamin down the road again...By the way any one need a cheap OEM fuel pump bought it last night, and I dont need it LOL.

thanks for the input on everything

 

Seriously, Put it in the FS section. With all the fuel pump probs I see on this board, I bet it'll sell in 2 days.