-82 petcock ON drains fuel below RES level

[Rikard]

I have an -82 Vision (European version) that seems to be leaking fuel from the reserve inlet on the petcock filter/screen to the main inlet.  That is, even when the petcock is in the "ON" position, the fuel tank will drain completely when the engine's running.

Petcock is in good condition otherwise, no leaks when fuel line removed (except when in prime, naturally), diaphragms seem ok (vacuum works, no visible cracks or tears), the round rubber seal with four holes doesn't seem worn.

Looking at the in-tank filter, I notice it's a really poor fit between the tank body and the filter, and also that there's nothing to completely seal off the reserve inlet on the petcock from the main inlet where the filter enters the petcock. The filter has the one 'tube' going down to the main inlet on the petcock. The reserve part of the filter is just an open hole.  The filter _seems_ to be ok - no cracks, no obvious broken off or missing parts.

I noticed in another post that there should be a 'reserve tube' going up from the petcock into the filter - is this true for the -82 or just the -83 petcock?

Anything obvious I should check? Should I use some sort of sealer between the filter and the petcock body?

thanks in advance,
Rikard

[Lucky]

since we are talking about an EU version here, we need to clarify which patcock you have.. i'll refer to them as 82 & 83 according to U.S. versions since most of the members of this site are U.S./ Cdn

82 petcocks have 1 fuel line & one vacuume line  the plastic tube that sits in the tank has different chambers for "on" & "reserve".  they really aren't much of a filter & you should be using a filter between the petcock & carb (83 too)

83 petcocks have 2 fuel lines & 1 vacuume line the plastic tube on the 83 is the same, plus there is a second taller tube that is for "return" fuel (not reserve)
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Now, if you can drain the tank with the petcock on "ON" & all the rubber bits are in good shape then the "on/res" tube is broken inside (perhaps someone modified it?), missing, or so loose in the petcock body that fuel can actually bypass it.  if the "retun" tube (if it's an 83 petcock) is loose, then fuel could drain back into the carbs, but this SHOULD only happen when the bike is off, & the diaphram leaks...

you can pop the 'top' off the 'on/res' plastic tube & look inside to see how it has two chambers, & poss tell if it's been modified or drilled out by some unknowing person .

other than that the only way you can run the tank out on "ON" would be a leak in the rubber pieces, or severe corrosion in the carb body causing an internal leak.

perhaps "res" doesn't work at all & you only think the tank is empty?

--Lucky

[Rikard]

Ah, thanks, I was hoping there'd be some way to fix it easily. 

I have the standard -82 petcock, no return lines.  I think it must definitely be that the 'filter' is a poor fit in the petcock. I'll try to fit a small o-ring on the tube that goes into the ON-hole in the petcock. That should be enough to seal it. Actually I'm a bit surprised that's not a factory default (which I take from your post that it isn't?).

Oh, and yes, I'm sure reserve isn't working, for two reasons: one, I emptied the remaining fuel in the tank after running dry - less than 40cc (0.4 litre) of gas left; two, the on/res/filter/whatever  ;) in the tank is spotlessly clean, whereas the inline filter (which I replaced the day I bought the bike) is gritty and generally filled with flakes of rust (which, in turn, means POR-15 as soon as I don't need the bike to get 'round on come winter)...

Great! Now to get rid of all that gas in the tank... Hm... I guess I'll have to go riding..  8)

[Walt_M.]

Really sounds like the tube inside the tank is broken or missing. I haven't seen one for an '82, maybe Lucky has one?