Mystery fuel leak 2013 v7 stone

[Elliott]

Hi folks,

Seeking your collective wisdom on a mystery fuel leak!

Running a 2013 v7 with just under 4k on the clock. Last few times I've head out to the garage to fire it up, I've found fuel all down the left hand side side cover (to the front only, as though it's been cascading down) and on the exhaust pipe and garage floor immediately below. There is also a trace of fuel on the lowest point of top of the fuel tank on the right hand side - e.g. Where it meets the seat/ where your right inner thigh would be when sitting on the bike.

It's not the quick coupler (the one with the green tab) as my bike has the later replacement single unit fuel line ( the coupler on mine cracked a while back causing a non-mystery fuel leak!). There is no evidence of a leak at the red fuel pump nozzle or its coupler or the fuel pump gasket with the bike cool/at rest. The tank overflow hose is properly connected and secured with a fastener - no visible tears or kinks in its routing. And yet somehow what seems a significant amount of petrol is finding its way out, seemingly starting high enough for some to pool on the top of the tank whilst the rest makes its way to the left hand side cover via gravity,

I know some similar year Grisos have had a problem with the fuel pump assembly gasket and this could explain the side cover and floor deposits but not how would it get up high enough to bead on the top side of the the fuel tank? Can anyone suggest further suspects to investigate?

Thanks

E

[sib]

Could the leak be at the big, oval, expensive gasket where the fuel pump assembly is attached to the inside left surface of the tank?  Did you check whether the 6 fastening screws are properly tightened?  They require 5 Nm torque.

[malik]

Could it be pressure & coming out past the cap? You could try taking the cap off overnight after a ride & see if it still does it. You might get a whoosh when the cap is first removed. Keep us informed.

[Kev m]

Does/did this only happen with the tank full?

 Is the tank overflow hose CLOGGED?

Could it be coming through the cap assembly in some way?

[O]

Perhaps this issue Pete reported a while back:

http://wildguzzi.com/forum/index.php?topic=71393.0

[Elliott]

Thanks all for the suggestions. The culprit is a hex bolt on the underside of the tank next to where it bolts to the frame. There look to be 2 depressions in the head of this which seem to have been tacked prior to painting. One of these tacks has rusted and the petrol was seeping through the rust at a very slow rate. Nonetheless it would accumulate and with the bike on the side stand it would run down the underside of the tank and then down the left hand side cover, dissolving the tank mounting bolt rubber as it went.

Couple of pics below in case this helps anyone in future. Be interested to know if all V7 tanks have this hex bolt and if so whether the two tacks are also standard or if this was a factory fix for a damaged bolt or something. Worth mentioning the paint had softened but not peeled off the bolt despite the leak so damage/rust was not visible on inspection. I exposed the area (just took a rub with my finger though) for the purposes of illustrating the weak point. Dropped tank for repair today, quoted at £60-£80.

https://flic.kr/p/TFaxkF

https://flic.kr/p/TFaxzZ

https://flic.kr/p/SoCxym
 

[sib]

I just looked over the pics I took of my '13 Stone's tank, which I took when I changed the fuel filter.  Sure enough, there's a hex bolt there exactly like yours, except mine didn't leak.  I'm glad I took the pics, because I sure don't remember seeing that bolt.

[Elliott]

Finally had tank back so thought I'd post an updated pic.

https://flic.kr/p/UPGvBi

Replaced the stock fuel filter with a Mahle KL145 before putting the tank back on because lemonade!

[TimmyTheHog]

oh boy!

So happy this thread resurfaced!

lol...gonna change my filter next week and this adds another thing for me to check :P

[redhawk47]

Perhaps this issue Pete reported a while back:

http://wildguzzi.com/forum/index.php?topic=71393.0

I couldn't post to this referenced thread because it is in the 2014 archives, so I am posting here.

2016 V7II Stone: pulled the tank and checked the pucks - one loose and one tight screw. Fixed.