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ZZR250 - Bike flooding while off?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Linux_insidev2, Nov 5, 2007.

  1. Hey Guys,

    Twice now this has happened, after going to a party my bike won't start - these parties were like 6 months apart and both times the bike flooded (I suspect some dickheads thought they'd sit on it and play around).

    My ZZR's fuel system is apparently vacuum operated, and i've been also told that while the bike's off it shouldn't be able to be flooded, however my father says it is indeed possible, and the proof is in the pudding.

    Is it possible? if not what else could cause this?
  2. If its been dropped, that'll flood it :)

    I dont know if moving the throttle will actually pump it in some small way, if it does than that would explain it - some random would come along pretending to revv it, pumping petrol into it and flooding it. But I'm not sure if it does that..?
  3. Vacuum fuel taps can fail and cause flooding. I suggest a fuel tap rebuild, parts available from big K.

    Regards, Andrew.
  4. Cool, so it's just a coinkydink that people must've been playing with it? or is it linked?

    I suppose I should replace the seals and the filter while i'm at it.
  5. ssomeone could have flicked it to prime, but if it wasn't there when you got back, I can't see it doing any damage.
    Had any other issues lately? Bad fuel economy, hard hot starts, don't need choke for cold starts? Random bad idling/flat spots?

    Regards, Andrew.
  6. was the fuel tap left on prime?
  7. The diaphram in the fuel tap could be buggered
  8. I think it goes like this.

    If you unplug the fatter hose from the petc0ck (fuel tap) what happens? A little fuel should come out the hose and a few drips (then stop) from the petc0ck, (so have a glass jar handy to catch it).
    If its pissing out you need to fix up the diaphragm. Try changing it between the On res and off (or whatever positions they have on the ZZRs). It shouldn't flow in any of the positions without the bike running...
  9. When I pulled the hoses off and removed the tank on the weekend, there was a little bit of fuel under the tap but not much, even after having it unplugged for ages.

    However, It has never needed the choke - the choke kills it (runs way too rich I think) fuel economy has been fine - been getting at least 350k's a tank with my weekend rides.

    Tonight, I had what I think is an unrelated issue - My bike wasn't idling properly, it dies off slowly after a few seconds and to get it back to normal you've got to open the throttle a fair way - then it goes back, but the idle adjuster came off the bracket and may have wound or unwound and caused it to run rich while warm, the bike only did it after I'd gotten it home - not when I started it and warmed it up to leave the train station.

    I work the late shift anyway, tomorrow I'm pulling her apart again to adjust the idle screw (parts coming so I can mount it back where it should be :p ) and I think the tap might be leaking a little still - If I order new seals and a filter this should resolve the issue right?
  10. For those interested i've located the fault.

    One of the cylinders is flooding because there's a fault developed in one of my carbies (I experienced a hydrolock trying to start it this morning) , it appears to be the float needle at the moment, I've ordered a new needle, and float bowl gasket for the carbies and i'll be tearing down the bike on the weekend and cleaning the carbs and replacing the seals and needle.

    Lucky I have my dad to help, I'm not the most mechanically minded person but I aim to fix that :p
  11. :(

    Damn, hydrolock, there was no damage was there? the bike didn't make any wierd noises?

    And you may want to replace the oil while you're at it, excess fuel contamination?
  12. No Damage done, the starter can't be strong enough I reckon.

    It hasn't happened while running (thank god)

    I'll do an oil change yeah, had one done only a few thousand ks ago but the tools didn't replace the washer on the drain plug and it's leaky :(

    Probably a latent issue with the carbs from a bad lowside I had when i bought her, the choke wasn't working ever since then, i guess I found out why :p

    One thing I do not understand is that now when running down the road, 4k's to the station the thermofan kicks in - it never used to, but this may be because the bike has to idle at 3k to stay running.

    I might catch a bus until the weekend when I fix it.
  13. O.K, this is what I was trying to find out. You have two failsafes for a hydrolocked engine, fuel tap and carburettor needle and seat. Both have failed you here.
    You need to rebuild your fuel tap, install a proper fuel filter (needle and seat failure is usually gunk on the sealing surfaces, or damage caused by gunk) and you may as well rebuild, or have rebuilt, the carbs, as they're going to have to come off anyway.
    Hydrolock can ruin an engine just like that. If you suspect you have fuel in a cylinder, DO NOT HIT THE STARTER. A bent rod is very possible. Pull spark plugs and crank engine first.

    Regards, Andrew.
  14. yeah the fuel tap will have to get done, and put an inline filter in that's easily replaced rather than the one that's built into the tap.

    I won't be riding the bike any further until the carburetter is fixed.
  15. Guys you are peeing before your water comes here.

    As noted, it just may be that someone played with the fuel tap and set it on prime for a while.

    If it's still flooding after you've put it back to "on" then it could well be a bit of dirt under the seat within the tap.

    Now the needle isn't seating probably because of dirt under it, so this follows on from the tap. You got a lump of crap in your tank.

    So you didn't need a new float needle and seat, though it won't hurt. You just needed to give it a good clean.

    Same with the tap. I wouldn't be doing a tap overhaul. Just pull it apart and give it a good clean.

    Also I'd be changing my oil, if I got that much fuel in the top end.
  16. The reason for the new needle and seals is that if they do indeed require replacing, i don't want to be pulling the bike apart again.

    The bike hydrolocked at my house with the tap set to on, and being that the bike is 8 years old I don't know what state the carbies are in.

    It's a chore to get the carbies out of my bike, so it may aswell be done now and get everything cleaned and checked to make sure i don't have to pull them out again.

    re: tap - the taps been leaking for a while afaik, i need to change the filter which is in the tap itself, may aswell do everything at once.

  17. Sorry mate, if it's that far advanced it hydrolocked, it needs to come apart. That's a lot of fuel in a short time, I bet carbs are FULL of shite and turning it over dislodged it all.

    Regards, Andrew.
  18. In that case it won't pass fuel when the engine is running.

    (Just had that on the VTR250 and just replaced the D, at $58!)

    Leaving the tap on Prime won't cause the problem unless one or more of the needle and seat valves in one or more of the carbs is dirty, and not seating correctly.

    That will then allow fuel to flow through continuously and cause the flooding. The fuel tap valve which the tap diaphragm is connected to could also be dirty or damaged, and not fully closing when the engine is off.

    All this is relatively easy to check:

    1) Remove the fuel line from the carbs (when the engine is "off") and see if any fuel continues to run through. It should stop after the fuel in the line drains away.

    2) Turn it to Prime - fuel should run through.

    3) With the fuel line disconnected and pointing into a container, start the engine with the tap on main or reserve - fuel should run through and stop when the engine stops. You only need a second or two of running to see this work.

    4) If all this functions as it should you could still have carby flooding because of worn or dirty needles and seats - what mileage have you done? Bear in mind that this flooding could only then occur on Prime while the bike is standing.

    If you change the needles and seats, or even just clean them (which should be sufficient) you should also check and set the float level while you are at it. The measurement for this will be in the service manual.

    Japanese carbs use a spring-loaded valve with a wear-resistant tip - they do get dirty but seldom need replacement. They are normally still fine at 50,000 km.

    If the bike still runs after the hydraulic lock things are fine. Our VTR250 suffered one (several, actually) from oil entry via the breather after being tipped over. It still runs very well 3,000 km later. :) I guess the starter motor does not have enough grunt to create the usual damage

    Hope this helps :)

    Trevor G
  19. Not on most bikes, unless they have accelerator pumps, like a lot of large Dellortos and, I think, some Bings. I think one or two of the larger Jap tourers could have had carbs with accelerator pumps (which squirt raw fuel into the carb venturi every time you open the throttle, even when the engine is not running) but this is very rare, and not used on "tiddlers". ;-)

    In other words, on virtually all Jap bikes with carbs, opening the throttle does not richen or flood the cylinder.


    Trevor G
  20. It's not really a fuel filter - not like the type used in cars, which are much finer because they operate under fuel pump pressure. Unless it has holes in it there is no point in replacing it. It is easy to clean and unblock.

    The real issue could be dirt/crud/muck/"shellac" as it is sometimes known in the fuel tank itself. The latter appears to be a byproduct of dirty fuel storage tanks and looks like transparent butterfly wings!

    In any quantity it will cause problems (usually blockages rather than flooding) but you obviously have something in there which is fine enough to pass through the fairly large pores of the coarse filter. Try cleaning the tank when it is off, even just letting fuel flow out after you remove the tap.

    It is unwise to attempt to fit an automotive style fuel filter inline - these are designed for pressure feed systems rather than gravity feed as on most bikes. They end up not flowing enough fuel with resultant overheating and even engine damage from a lean mixture.


    Trevor G