hey guys. i just got a 91 cbr1000f. and it wiil not stay running. i cleaned out the carbs 3 times and still does not run. well it will run when i first start it up, but then bogs down like its not getting fuel and dies. i seem to be getting plenty of fuel through the petcock. i removed all vacume lines for the emission control and plugged all vac. ports on the carbs except for the one running to the petcock. (is that ok to eliminate all the vac lines???) when i first start it it runs perfect , it just seems to be running off of the fuel in the bowls and then dieing. after it dies it will run but only on choke, and as soon as i hit the throttle it dies. please help!!! im ready to ride this beast!

 

Just a thought , but try running it with the petrol cap open , some guys have had trouble with a vacuum being created in the tank so fuel is slowly cut off , also check for any crimped fuel lines under the tank.

 

Good idea hawkwind.

After that I would pull the fuel line and put a vacuum to the petcock and see if gas flows freely (I use a brake bleeder tool to create the vacuum needed). If so then I would loosen the drain screw on a bowl to see if gas runs out of the bowl freely.

You must have a California model if you had vacuum lines.

 

Are you sure you're getting vacuum to the petcock? If you follow Hawkwind's advice and get fuel, it might be a good idea to check the line you have put to the petcock for leaks.

Edited to add: if you're getting crud out of the carbs every time you clean them it's time to clean the tank and put a fuel filter in line.

 

wow u guys r quick! just got back in from working on the hurricane. i let it sit for a while with the gas off and tried to start it but it wouldn't turn over. number 2 cylinder was full of gas. took carbs back off again to see if the float was sticking and it moved freely. i took the gas line off and used my mouth to create suction and gas flowed freely. but it might be a different story when i put the fuel line on. i also pulled the plugs and they were black..... was not surprized. i put a new piece of vac hose on and still nothing. i wounder if the diaphram in the petcock is bad? i looked and it looked fine.

 

So when you suck on the vac line to the petcock, the fuel flows freely through the fuel delivery line?

If you have a California model (PAIR?), then I'm not sure if you can just plug all the lines off... I removed my PAIR system and left some stuff connected because it wouldn't run right. I may be able to help you out a bit...
Fuel filling a cylinder when not running is all wrong, though, and shouldn't have anything to do with the PAIR. Sounds like either the float is sticking or the float somehow got filled with gas, maybe?

 

yes i have fuel flowing freely through the petcock. so do u think i should reconnect all vacume lines. when i had the carbs apart i made sure there was nothing in the floats. maybe i could put them in a bowl of gas and see if any of them sink??

 

Only 12V at the battery ?
Hmmmmmmmmmmmmmmmmmm maybe try a jump start and then perhaps a new battery..........

 

Excellent question CBR Classic. I've never dealt with a California model CBR, but back in the '70's when people were in the habit of taking off 'all that emissions crap' we'd get cars in the station that just wouldn't run right until we put it all back on. One has to know how the total emission system works to mess around with it and leave the engine running right.

So, Ironman, you pulled everything off. You've had the carbs off and back on. Ummmm, are you sure you didn't put the fuel supply line on the carburetor vent port and the vent line on the fuel inlet port on your carbs? It can happen, and if it does, you'll get exactly the symptoms you describe (please, don't ask how I know).

Otherwise, stuck float valve, flooded float, incorrect float level, dirt holding a float valve open, etc.