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Help: Fuel/Breather Hose Confusion

Discussion in 'Technical and Troubleshooting Torque' started by mattb, Oct 16, 2006.

  1. My bike (Kawsaki GT550 '83) hasn't given me a single problem, as far as reliability goes. On the weekend I undid the bolts to the fuel tank to lift it back and inspect some cracks in the frame which I've just discovered. I didn't remove the hoses to the tank, just the bolt and lifted the tank back slightly, and so figured it was fine simply to bolt back on.

    An hour later I got on the bike and rode off. Within a couple of hundred mtrs she began to lack all power and, it seemed, was starved of fuel. I pushed it back home and lifted the tank again. Started the bike (or tried to) and my housemate saw petrol come out of a lose hose (call it 'A'). We noticed a secondary hose nozzle on the fuel tap, and figured that must hook on. This seemed odd, as the hose seemed to be sitting a long way (on the opposite side of the tank) from where the tap was sits. Did that, jump started the bike, and it only ran with full choke on, then when we turned it off, and tried to jump it again, it simply wouldn't start.

    At this point I discovered I've lost my Haynes manual.

    Yesterday, took the tank off with a mate, and noticed taht there was another hose (call it 'B') which leads into the engine, whereas hose A leads into the carbaretteur. Figured this shorter hose B, which is in just the right position and bent back as though to go into the fuel tap, must be the right one. We also discovered that the fuel would not flow from the tap when 'on', but does freely when in the 'reserve' position. A multitude of problems, but I'll ignore that for now, as long as the fuel does flow.

    THen saw that there is another hose leading from the carbs, in mirror position to hose A, and it seemed purposely tucked away to nowhere - as though it's a breather pipe or something.

    Hooked everything back up today (my mate broke the fuel filter yesterday, so work stopped), and turned the tap on, without starting the bike, and lo and behold fuel came freely out of the now loose hose A. But hose A seems to mirror the hose coming out of the other two carbies, which goes nowhere. So which hose should I plug in to the fuel tap? Hose A, which spills fuel, or hose B, which seems obviously in place to plug in to the tap. Again, hose A plugs into the carbs, hose B into the engine part in front of the carbs.

    It ran with hose A plugged in, but then wouldn't at all, and only ran with the choke full on. So I speculate that it would have ran ok with the reserve on, had i tried it. But hose B then, is disconnested, and seems to obviously go into the tap!

    I hope my descriptions have not been too vague.

    Cheers, Matt.

  2. by the sounds of things looks like you have a vaccum reliant fuel tap which alot of bikes have.

    two hoses plug to these a fuel line and a vaccum line.

    so the hose that goes to the carbs is the fuel line and that should plug into the nipple that petrol was coming out of on the fuel tap.

    so the remaining hose should plug into the remaining fuel tap nipple on the engine side of the carbs hole that you mentioned earlier.

    hope this makes sense and goodluck
  3. Apologies for hi-jacking this thread, but it seems I have exactly the same problem. My 85 SRX 250 has a 'vacuum reliant' fuel tap that isn't working, we're going to have a go a fixing it, but if it's cactus, will I need to find a model specific replacement, or is fuel tap a fuel tap??

  4. if the SRX250 tap is similar to the SRX6 tap, you'll have 4 hose connections. two next to each other, towards the top of the tap, labelled 'on' (or 'run') and 'res'. These are the fuel inlets. You'll have another towards the bottom (not sure if it's labelled) for going to the carbies.

    The 4th inlet is slightly below and perpendicular to a flat section of the tap. This is the vacuum line. It will run to the inlet manifold (between carbie and cylinder). it works by using the negative pressure (on intake stroke) to pull a rubber membrane away, allowing fuel to flow through the tap. the 'prime' position bypasses it.

    my advice would be to take it off the bike, take it apart (being careful to note what went where!) and give everything a good clean in new petrol. As for a replacement, they all work on the same principle, but you might have trouble finding one that fits. check with your local wreckers. I don't know for certain, but i'd guess that, like fuel caps, there'd only be one or two yamaha designs that are shared between a lot of models.