Fuel leak from drain hose?

[dr]

Hi all,

I'm a new member of the forums here -- just bought a used 1989 GS500E and I've got a problem.

I came home from work yesterday and noticed an unusual smell coming from my garage. I opened it up and noticed the motorcycle sitting in a decent-sized pool of fuel. I looked the bike over to try to determine where the leak was coming from, and there turned out to be a rapid drip coming from one of the drain hoses on the right side, clamped next to the base of the engine.

I had a look at the repair manual, and it looks like the two hoses mounted there are the "air cleaner water drain hose," and the "fuel tank water drain hose." I can't determine from the picture in my manual which is which. But there is definitely a difference: one is open at the end, and the other has sort of a phallic-looking rubber tip at the end. The leak is coming from the rubber-tipped one -- there's a small crack in the tip.

So here come the questions:

1. What is that rubber-tipped hose, and should there be a crack in the tip?
2. Is it at all reasonable to expect fuel to be in that hose (crack or no crack) and assuming the cracked tip is normal, is it reasonable to expect fuel to leak from it?

Some more background, by the way: The guy I just bought the bike from told me to always leave the fuel petcock on PRI, because the engine gets starved or bogged down or something if you ride it in the ON position. I've read that's a common problem in the early model GS twins, so I wasn't too worried. But I can't imagine leaving it parked in my garage on PRI is such a good idea...

Also, I've read phlooke's post that seems similar to this. After discovering the leak last night, I basically followed the same steps he did: tried to start the bike (which was difficult, but I was able to eventually), then turned it back off and left the fuel petcock switched on ON instead of PRI. Maybe that'll help, but I think I need to give it a few days to see if the leak manifests again. The thing I was mostly confused about -- that made me unsure whether I'm having the same problem as he did -- is which hose is which! If the hose my bike is leaking from isn't the airbox hose, then I'm still at square one.

I'd be very grateful for any ideas you all might have. Thanks very much.

[The Buddha]

OK Pri ... will let fuel flow into the carbs without vacuum ... On and Res need engine running to flow ... your problem is precisely that ... Run it in ON ... fuel statvation is only as issue if you run it for long periods with Wide open throttle ... BTW somehting might be wrong with the vacuum and he might have used Pri to bypass that ... however leaving it sitting in Pri makes the carbs overflow, usually into the airbox and that drain with rubber tip is from that ...
That rubber tip If I remember does have a tiny nick in it. You run the bike in Prime ... but do not park it in Prime.
Cool.
Srinath.

[Jake D]

Sounds like you are going to have as much fun as I did when I bought my GS of E-bay!  

Keep reading this site. . . You'll learn everything you need to know.

IMHO, leaving it on PRI all the time is a bad idea.  What you may end up with is a "gas overflow incident" and a house that smells like shite.  Gas could back up into your airbox, or it could make its way into the engine case.  Check your oil level when you get this sorted out, it may have taken on a lot of gas and doubled itself.  You'll need to change it.  

Leave it on ON position, after you replace all the fuel hoses.  Yours are probably cracked and brittle.  They are standard sized.  Go buy like 6 feet of it at the dealership for a buck a foot and re-route them all.

[Kerry]

1. What is that rubber-tipped hose, and should there be a crack in the tip?

It is indeed the airbox drain hose.  (See the diagram at the bottom of my Fuel Hose Routing page.)
The photo below shows the area that is drained by the other, thinner, cap-less hose:

2. Is it at all reasonable to expect fuel to be in that hose (crack or no crack) and assuming the cracked tip is normal, is it reasonable to expect fuel to leak from it?

The "crack" is normal.  Not only may you get water from that hose (after riding through the rain, say) but you may also get a small amount of oil as a result of "blowby" from the short, thick hose between the valve cover and the top of the airbox.

It is NOT normal for fuel to end up in the airbox.  As I understand it, two things must occur for that to happen:

1) The fuel selector must be set to PRIme.

2) The float needle in one or both carbs is not closing tightly.  This could be because the float itself is stuck and therefore "asking" for more fuel even when the float bowl is full, OR the float needle is not seating properly and is allowing fuel to enter the float bowl even when it is "closed".  The second condition could be caused by dirt / varnish which prevents a good seal, or it could be caused by a worn needle:

[/list:u]Under these conditions, the fuel level will rise right up through the carb body (trying to reach the fuel level in the fuel tank).  Fuel will eventually spill over, either into the airbox or along the intake boot to the intake valve (and into the cylinder of the valve is open).  Having it come out of the drain hose is MUCH better than "hydro-locking" one of the cylinders!

If you have questions about any of that, post 'em here!

[dr]

Wow, only three hours later and already I have expert advice! I'm particularly glad to know the nick in the tip of the airbox drain tube is par for the course. This forum rules. Okay, so it sounds like I have a few things to do at this point:

1. Check the oil levels to confirm no fuel has flooded into the oil.
2. Leave the fuel petcock set to ON when parked.
3. Have the floaters and fuel lines looked at.

Basically, I'd like to be able to ride the bike with the fuel switch set to ON, since both PRI and RES leave me with no reserve. That's regardless of any of this other stuff, so I'm going to get that looked at in either case. But I'll be sure to have the float needle and levels examined to see if that's contributing to the problem.

Until then, if I find that the oil levels look ok, do you all think the bike should be safe to ride? All the tubing is actually in pretty good shape, not cracked or anything like Jake said, so is there anything else I need to worry about?

Cheers!

[Kerry]

Basically, I'd like to be able to ride the bike with the fuel switch set to ON, since both PRI and RES leave me with no reserve. That's regardless of any of this other stuff, so I'm going to get that looked at in either case.

Yep, good plan!

But I'll be sure to have the float needle and levels examined to see if that's contributing to the problem.

You could do your own pre-check by putting the bike on the centerstand and using the "U-tube method" to determine which carb(s) have the overflowing float bowl.  Still, with a bike that old I would make sure BOTH carbs got a thorough inspection and cleaning ... so you will have a known baseline to work from later on.

Until then, if I find that the oil levels look ok, do you all think the bike should be safe to ride? All the tubing is actually in pretty good shape, not cracked or anything like Jake said, so is there anything else I need to worry about?

_I_ can't think of anything else.  If you notice any other odd "symptoms" ... post up!  

[dr]

Just wanted to post back here for completeness, just in case anybody else runs into the same problem in the future...

I checked the oil level, and it seemed fine. The level on the dipstick was at F, but not above it, and the oil felt viscous to the touch and undiluted. So I think that ended up being a non-issue, thankfully.

I left the fuel switch set to ON and found no new leakage after a night ... Granted, the first time this happened, I had left the bike sitting in PRI for several days before the leak manifested. So I'm not 100% certain I've fixed the problem, but reading the postings here leaves me pretty confident.

I rode today. Probably a bad idea actually, since I just got my license, I live in San Francisco, and my destination was the doctor's office. But I managed to avoid getting myself killed, and more relevant to this post, the motorcycle seemed just fine. The GS500E's reputation as a solid workhorse is well-earned, I suppose!

Anyway, thanks again everybody. Hopefully that's the end of the story!

[cernunos]

On the topic of leaving the fuel selector in prime; another thing that can cause a bit of overflow is "bouncing" of the floats from moving the bike around or sitting on it while making vrooom-vrooom noises. I always leave Nicky with the lever in the "on" position, but I try to make a habit of moving the lever from time to time to ensure it doesn't freeze up. Love that little bike and this forum.

C.......

[John Bates]

........ another thing that can cause a bit of overflow is "bouncing" of the floats from ........ sitting on it while making vrooom-vrooom noises. .............. Love that little bike and this forum.

C.......

I do this all the time and haven't had any fuel problems.

:lol:  :lol:  :lol:

Welcome back cernunos.  I missed your good humor.

[cernunos]

So has Bebe  :lol: . Love the bike and the forum.

C.......