No Fuel When Hot, Vapor Lock?

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No Fuel When Hot, Vapor Lock?

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CBR Forum >> Past CBR Models >> CBR 600F2 >> No Fuel When Hot, Vapor Lock?

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No Fuel When Hot, Vapor Lock? - 7/1/2006 12:08:45 AM

fzsteve

Posts: 3
Joined: 6/30/2006
Status: offline

I've got a 93 F2 with a puzzling fuel problem.

When the bike gets hot, it runs the fuel filter out of gas, and quits. After it cools off for 10 minutes, fuel will fill the filter and it will restart.

I have been through the carbs multiple times, and the are clean. I have pulled the needles out, inspected the seals and cleaned the seats. I checked the operation of the needles, and the don't stick.

I have checked the tank vent and it works.

I pulled the fuel petcock apart and found the diaphragm was leaking and replaced it. I verified that it works by hooking up a vacuum brake bleeder to turn it on and off.

I finally re-routed the fuel filter and line so I could get good access to it during one of the "shutdown episodes". I found that when it shuts down, the fuel line is completely drained down past the filter. If I remove the fuel line, fuel will immeadiatly flow from the tank, so the blockage is up in the carbs somewhere.

HELP!

Post #: 1

RE: No Fuel When Hot, Vapor Lock? - 7/1/2006 5:45:31 PM

suream

Posts: 41
Joined: 4/23/2006
Status: offline

Sounds like the carb bowls are not filling up fast enough. There are two breather tubes for the carb bowls, if they are blocked or pinched they will not fill the bowls fast enough. If you can run the bike until it does it again then try to bleed the bowls, below the carbs are the bleeders for each carb...just turn them with a screwdriver until a drop of fuel comes out. Do each carb that way then try to start it. That may not be the problem but it is the next thing I would try.

(in reply to fzsteve)

Post #: 2

RE: No Fuel When Hot, Vapor Lock? - 7/1/2006 11:11:59 PM

fzsteve

Posts: 3
Joined: 6/30/2006
Status: offline

Thanks for the breather tube suggestion. Just happens that I looked at those this afternoon and blew them out with compressed air. they did not seem blocked, but who knows.

I also rerouted the fuel line and put the fuel filter so the discharge end is oriented up. I noticed today that a huge air pocket can form on that end of the filter if it is oriented the other way.

One of the two things must have worked, because I managed to take it out on a 40 mile ride without issues.

(in reply to suream)

Post #: 3

RE: No Fuel When Hot, Vapor Lock? - 7/6/2006 5:24:33 AM

mikequinn

Posts: 294
Joined: 3/30/2006
From: UK.
Status: offline

Fuel filters are directional for most bikes check to see if there is an arrow on it, thats the way the fuel should flow, but you don't really need a filter between the tank and engine as there's an adequate filter in the tank.
Just as a check, remove the filter and fide her for an hour and see if it cuts out if it does then it aint your filter.
Have you checked the tank filter for being blocked
Let me know how you get on.

(in reply to fzsteve)

Post #: 4

RE: No Fuel When Hot, Vapor Lock? - 7/9/2006 5:02:49 PM

fzsteve

Posts: 3
Joined: 6/30/2006
Status: offline

I took your suggestion, and removed the filter all together. This seems to have done the trick. I ran the bike in the garage for about 30 minutes on a fast idle to get the motor good and warm. I was actually able to get the fuel in the fuel line to form bubbles (some pretty big). without the filter, they harmlessly flowed into the float bowls.

It seems that the filter was capturing the bubbles and causing it to vapor lock.

Now my next predicament...what to do about filtering the fuel. I bought this bike as a repo, and it apparrently sat a while. The tank was pretty rusty, so I pickled it to dissolve as much of the rust as possible. I still have some of it floating around the tank, so I really need to filter it.

Any suggestions?

(in reply to mikequinn)

Post #: 5

RE: No Fuel When Hot, Vapor Lock? - 7/11/2006 6:17:02 AM

mikequinn

Posts: 294
Joined: 3/30/2006
From: UK.
Status: offline

just remove the tank, take the petrol cock off the bottom of the tank and swill as muck, rust, sediment out of the tank.
I know it's a ball ache but its the only way to get all that s**t out, or fit a new tank, you dont need a seperate filter as the ones in the tank do the job just fine.
glad I was able to help!