It’s why many monster owners for an external filter, the internal one can be a nightmare if it’s says around a lot
...hopefully found the issue. When I drained the tank there was about a pint of water mixed in with the petrol (as some of you may have expected).... Seems a lot but guess this may have been seeping in over an extended period and only becomes an issue when is reaches the level of the pump?? Anyway, all filter replaced, tank cleaned and bits reinstalled, half a gallon of fuel in....but flat battery now (must have almost flattened it with the constant restarting when I had the original issue) and its been sat a while. Will confirm tonight. On the tank leakage point, I couldn't seem to replace the lower cap with the o-ring in the groove - seemed impossibly tight but cant remember if it was there originally (and came out easily btw) so ended up seating the o-ring close to the rim of the lower cap - seems ok but would expect it at least needs another that sits in the actual neck of the tank between the tank and cap??? Also the opener itself doesn't look like its water tight. I would prefer to replace with a new locking one. Cant seem to find one on ebay for the S4. Do other models caps fit? Thanks again everyone!
Iirc, according to @Derek, tank o-rings always need to be replaced with new viton ones as they will have swollen (presumably from contact with ethanol) and can't be re-used
this bit could descend into controversy but I think the O.E.M. items (green) are viton? After careful inspection for nicks/deterioration I have re-used seals many times. If they are swollen to a point that they are not happy to remain in their 'housing' then replacement is obviously the answer but most of the swelling comes from using the wrong lubricants/solvents and even varying temperature. Using anything like WD40 will cause swelling and even too much rubber grease doesn't always help when re-fitting.
No suggestion that the oem items are not viton, merely that using any old o-ring is not advisable. The op complained that the o-ring in place didn't seem to fit properly - maybe it wasn't even the original OEM o-ring. The point I was trying to make was to make sure to get a viton o-ring if he is going to replace it.
I have had pumps in and out without replacing the o ring loads of times. BUt depends how old it is I guess. If you can get one, and have ti me, its worthwhile.
"On the tank leakage point, I couldn't seem to replace the lower cap with the o-ring in the groove - seemed impossibly tight but cant remember if it was there originally (and came out easily btw) so ended up seating the o-ring close to the rim of the lower cap - seems ok but would expect it at least needs another that sits in the actual neck of the tank between the tank"
There are 2 seals, an o-ring (21 in diagram) that makes the seal against the tank and an upper seal (18) which is more decorative and fills the gap between the top of the filler and the tank. The o-ring can swell and make the fuel cap assembly difficult to replace and is best replaced. There are two hoses attached to the underside of the filler cap. One is for the breather and the other for the filler drain. Make sure they are both clear through to the underside of the tank where they emerge. If the drain is blocked the filler neck will fill up with rain water which will find its way into the tank.
Those 'O' rings around the filler are a real PITA to fit, everything is so tight and it would be very easy to damage something doing it, I seem to recall seeing someone had actually dented the tank trying to get the filler back in? As for reusing 'O' rings, it maybe the old one will fit better than a new one after you've 'dried it out as it's already been in? and that particular 'O' ring isn't actually sealing fuel, other than splashes. As an example I have re-used the large 'O' ring in a 916 fuel pump base a couple of times. They are swollen when you remove them but if you let them dry out overnight they shrink back again and fit fine - maybe I was lucky but a a combination of impatience and 'how much?' worked fine...
Just for info, the green o ring for the fuel pump will shrink back to its original size aftrr a week or two and if not damaged can be reused. I have been using the one removed a year previously at service time with no problems for several years now.
As above I’ve yet to replace an original seal due to being stretched beyond it’s limit but it can happen. As said, variation in temperature is often the culprit and it’s usually that the seal, (the larger the worse-er) has expanded due to being ‘worked’ by hot hands and will settle down again if left for even a short period.
And it begins again........ Riding back today, bike seems ok (and last few days since fixed....or so I thought)....then......bbbrrrrrrrrr dead. Wouldn’t restart but tries to fire a little. The tank was half full...pushed it to petrol station and filled up hoping I’d just fitted the pump too high in the clip. Still nothing. The bikes been undercover and the fuel cap taped over to stop any rain leak..... Back to square one ....
Did you replace the filter? Could it be an air problem? I wonder if the air box pipes have a leak? Am sure I’ve heard of that before too on the earlier Ducati’s. Or not seated correctly with tank or breather kinked when you refitted.
Yeah. Changed filter. Just realised the battery isn’t in the best location to connect jump cables if you have a full tank.....tilted the tank to access battery and petrol flooded everywhere. Proper frank spencer. Thought best not connect the jump leads at this point....
Can I test a theory? When I replaced the fuel filters and cleaned the tank, finding about a pint of water in there, I put strips of duck tape overlapping the fuel cap which I suspect is leaking rain water in. The fumes from the tank seem to be dissolving the tape glue with trickles of white coming down the tank. Could this have leaked into the tank and either render the fuel useless or be blocking the filter or injectors? Is so.......what next? Dump fuel and force injector cleaner through system? Cheers!
I have no doubt that the fuel will dissolve the Duct tape glue but I doubt if there would be anywhere near enough to block the filter or injectors given that it would be dissolved in a (relatively) vast amount of fuel.
I’m not sure if this has been covered in the three pages of this thread, but have you checked that the tank drain line, The entrance of which is visible with the filler cap open, is clear? They nearly always block up at some time and the result of this is that even with fuel cap tightly shut, any residual water that gets past the cap and into the recess below eventually forces its way into the tank.
Let me get this right, you have used duck tape over your fuel filler cap for a while? Petrol will dissolve the glue however if the dissolved glue got in to the tank it will be suspended in the fuel so could be solidifying within the injectors, (a loose could)
