Fuel Valve Testing Help!!
 

Hi again guys.

All ready to go with my bike now and ready for the big test start. FAILED

I am not getting any fuel past the fuel valve. I know it operates with a vacuum but is there anyway to test it. I have put 5L of fuel in what was a completely empty tank. I assume that is enough to allow fuel into the valve? The fuel gauge is completely zeroed out in the red zone (but that may just be a faulty sensor)

Any help would be much appreciated

Cheers.

There are 2 hoses connected to the fuel valve. One is large (fuel line) and one is small (vacuum line).
If you remove the smaller vacuum line and suck on it, fuel should flow through the large fuel line.

Excellent advice from a Kilgoretrout ;) :D

If there's one thing I know how to do well.... it's make a mess with fuel. :D

What Trout didn't tell you -
remove the end that attaches to the tank - NOT the end that goes to the carburettor. Then suck on it........................
Which may explain why Trout ends up with fuel in his mouth HEHEHE

There's also a third connection on some of our bikes - the one I'm referring to points straight down. It has a hose which runs out either to overflow on the road, or somewhere on the carbs. To me it doesn't have any value, but if you confuse the hoses you still won't get any gas.............

Tried that last night but still no fuel coming through. I can hear the diaphragm moving when I suck on the pipe. Has anybody done a stripdown on the petcock valve. It is a Keihin make (same as the carbs). I cant seem to find an exploded diagram of the valve anywhere. My bike is a 1997. I have seen some rebuild kits online but only seems to be the diaphragm side. I think my blockage problem is within the valve itself (possibly hardened fuel residue)

Good that you guys have confirmed that fuel should flow when sucking on it, I was not too sure if I was generating enough vacuum, but if you guys have seen and done it then that's good for me.

Are we all happy that 5L of fuel added to a COMPLETELY empty tank is enough to hit the outlet for the RESERVE valve position?

Thanks

1st question.

Have you pulled the valve assembly out of the tank and thoroughly cleaned out the intank filter that stops the rust and any other cr4p that accumulates inside the tankfrom getting to your carbs?

May well be a good idea to do that before attempting to get fuel through the valve as a blocked filter will really stuff things up.

I personal can't suck hard enough to get fuel to flow. I may not be as worldly experienced as others.LOL

I use a hand held vacuum brake bleeder to open the petcock.

Just a reminder: fully CCW (12 o-clock) is on, fully CW is RES (6 o-clock) and in the middle (3 o-clock) is OFF.

Are we all happy that 5L of fuel added to a COMPLETELY empty tank is enough to hit the outlet for the RESERVE valve position?
It should be but if your reserve is blocked maybe not. The bike leans towards the fuel outlet, so....................
Try opening your tank cap - maybe a blocked air release pipe too - it happens.

It sounds to me like there's a blockage there and it's not related to the vacuum - possibly in the tank. This is what your fuel tap looks like inside. It's not really clear in the pics but both main and reserve have filters which are covered with a fine (very) filter and have an internal filter as well, so any clogging of these will cause your fuel flow to stop.

I may not be as worldly experienced as others.LOL

And TBT had a sheltered upbringing :)

Thanks to all for the advice. I stripped down the petcock valve last night on the kitchen table (wife was well happy!!). The diaphragm and rubber valve seat are connected by a stainless steel tube (all 3 connected as a single part). I went behind the diaphragm and pulled on the (what I now know to be) the seat rubber. It made a popping sound and I thought i has damaged it. In fact the rubber had actually bound itself to the seat (bike has been idle for 8 years). Tested it on the table by sucking on the tube, worked perfect (in both reserve and ON positions)

Got the bike started last night (FANTASTIC:icon_smile:) but then there was fuel leaking in the area of 3&4 carb and bike dies at low revs (:icon_frown:). Had a look on the forum and maybe looks like a sticking float. Hopefully get more detail over the weekend, hopefully don't need to take those bloody carbs off again!!

Once again thanks to all who contributed.

Maybe a post coming soon re the fuel leak.

If the bike has been sitting for 8 years,the Oring seals on the fuel feed tees and/or the overfolw tubes will probably need replacing, sorry but that means carbs have to come off, all very character building but not too difficult if you go about it in a methodical way and basicly demount but not necessarily remove battery box, air filter box, cables etc and wriggle wriggle wriggle the inlet tubes and pull back the filter case and then wriggle (does this sound familiar?) the carbs off the head . there is enough space to pull the carb assembly out.
Separate the carb assembly noting what goes where and reassemble using new Orings on both tees.
Refitting the carbs is easier if you use some sort of rubber compatable lubricant (KY maybe) joking. Hand cleaner soap gel or similar works well and just reverse the wriggle wriggle method while pushing the assemblies forward.
Good luck
Go well
JK

+ 1 with JK's O-Ring recommendation

No problem, man. And ya know, I think my valve needs cleaned/rebuilt as well. I think it's sticking like that intermittently. Probably from crappy gas over the years.

But yeah, likely the o-rings leaking. Like TK said.... :(
You'll probably just want to do an entire clean up while you've got them off. Oh, and it's easier the second time if that helps any. lol...

Oh and if you do get into the replacement of o-rings on the T's
watch for flying buttlerfly tension springs once you separate the
carb bodies to get the T's out

I'm having a similar issue of fuel not flowing from the tank. I have a clear fuel line, and it's completely dry. I've tried sucking on the fuel valve vacuum tube with no luck.
First I disconnected it from the carb and it wouldn't draw at all (this is the suggestion I originally read elsewhere). Then I connected it to the carb and I could get air flowing but the fuel still didn't flow. Any suggestions?

Background: '91 CBR600 F2, sat in previous owner's back yard for two years under a tarp. He claims he drained the carbs and tank before putting it back there. New spark plugs, battery, coolant, hoses, and fuel line. Still trying to start it for the first time...

Thanks!

Firstly, welcome to the forum.

Most scenarios are already covered in this thread for fuel flow problems from tank, maybe start another thread in the 600 section to get some different ideas on your problem.

Welcome to the forum.

You may want to take it apart to see if its got blockage or is dry and stuck.

Thank you guys. It was indeed dry and stuck but not rotted. Cracking it open was all it took.