Hi guys. I am new to the forum having recently bought a new to me 95 CBR 600 f3. At first I thought I got lucky and it was a great running bike. But I've had a lot of trouble getting it to run right all the time. I'm currently trying to rule out my fuel pump as an issue. I've searched a lot here and there are some that say it should pump every few seconds and others seem to describe it as a fast paced pumping you should feel. So I guess my real question is should it pump slow or fast and/or is there something that controls its pump rate that could be just causing it to seem bad. I've also looked into the "fuel cut off switch??" but again no one seems to be extremely specific as to what it does, how it does it or when exactly it should be doing it. Sorry if I make anyone repeat themselves.

 

This will answer your question as far as rely's go
Automotive Relay Guide | 12 Volt Planet
And basically a 12v petrol pump use's a spring and a diaphragm to deliver petrol when the carb asks for it, once the float needle cuts off demand to the carb ,the pump is in a balanced state and will not run, try pulling off the fuel line to carb on the petrol will flow continuously through the pump once the ignition is on

 

OK thanks. I thought that would be correct. I've been taking great care to basically have my hand on the pump at all times when test riding. My pump is about as erratic as Wiley coyote. At any given moment low or high rpm (and I do not rev it very high right now since its sick) it will stop all together, run steady, or race so fast it just hums. So the pump works it seems to me. So I should be looking at the fuel cut off switch, right? And is it correct that its the smaller black box mounted on the right side of the tail section.

 

When you take of the fuel cut off switch ,do you mean the relay, and yes its under the seat on the frame, if you bike is surging that's more likely to be your carbs than anything else

 

Yes. I have seen on here people reference it as both a fuel cut off switch and relay. That was part of my confusion. Yesterday though I confirmed that the previous owner had replaced the rectifier/regulator, the relay for the pump and the ecu(or what its called on this bike?) due to them being wiped out when they laid it down. However the harness plug on the ecu was not. Two of the wires were broken or frayed at the connector holding them in the back of the plug. So I took it apart, cut to fresh wire and recrimped the male connection pins, then put the plug back together. If I'm correct one of the wires was going to the relay and the other was going to what I believe is a throttle position sensor on the side of the carbs. On my test ride I didn't seem to get any flooding so I think I found the issue. But I'll have to put some miles on before I trust my results. And I have to change my plugs. I believe I may have fouled one or two due to it flooding so much previously.

 

Sound's the way to go

 

Well... I'm still pretty sure my pump is OK. But I've definitely not fixed my flooding issue. I just cleaned my carbs but they seem to be suspect number one. After trying to go for a test ride and it still running like crap I decided to pull my air box again and have a look. Good thing I did because I found cylinders 1 and 2 full of gas all the way to the top of the carb where the velocity stack mounts into the throat. Definitely not what I wanted to see. So this time I am not going to just clean them but rebuild them as well. I pray this fixes it because I do not think my engine can handle being hydro locked again.

 

Well guys. I hope someone out there will have some brain storm of an idea. Pulled my carbs off to prep them for the rebuild today and decided I'd check the floats first before starting any disassemble. When I blow in the fuel nipple on either pair of carbs they work without fail every time. Up air passes through fine. Upsidedown I can blow as hard as I can and nothing, just hurts my cheeks. Any ideas of an alternative source of flooding.

 

Have you taken all jets and needles out for a good cleaning, if your cylinders are full of fuel your float needles want looking at along with float height

 

^
I concur with this! Sounds like your floats are stuck