by annageek » 06 Feb 2016, 10:45
Sorry to disappoint, but I can't recall ever smelling petrol in the cuddy on our 19GTS. Not to say that all are equal! I can't even remember smelling fuel (however faintly) when working in the engine bay. That said, up until recently the flame arrestor has always been so gunked up with oil that it may well be an effective seal against low pressure gas (petrol fumes) sneaking out, and therefore trapping the fuel smell in?
Assuming the worst and you have a leak, having completely replaced our tank with a bigger one, it strikes me as though there are several things that could potentially have happened.
To access the tank is a bit of a pain. Basically you have to lift the whole deck sole up - The screws round the edge of the sole will do it - however, if your boat is anything like ours, the captured nuts that the screws tighten into, they'll have rusted up and seized to the point they'll still turn but won't fully undo, making drilling them out impossible (I think the captured nuts were stainless, but the capturing part was galvanised steel!!). Al are accessible, but difficult to reach. You can get to all of the rear ones from the big centre hatch, a helper armed with mole grips and slender arms may well help! For the forward screws you need to remove the lower carpeted panel attached to the bulkhead inside the cruddy. This is just screwed in, but the carpet hids the screw heads, so it's a bit of an easter egg hunt trying to find them all! With this away, you should have good access. Finally there is one screw on the diagonal part of the cockpit sole, behind the helm seat. On ours, we have a factory fit speaker in the seat-base just above it - with this speaker removed, I could just about get the mole grips to this offending screw too. In all, of about a dozen screws, I think only 3 came out without having to get onto their nuts with the mole grips!
The sole will now lift up - once you've fought the silicone sealant holding it down.
The fuel tank is fitted in a water tight cavity. With ours, I was surprised to find about 6" of water all around it - my guess is some of the cockpit sole sealant was imperfect and had leaked. As such, the water, which had probably been there for years, was slowly but surely causing pitting corrosion where there were any close fitting parts of bulkhead/straps/wooden batons holding the tank down! I think the tank is 3mm 6061 aluminium and some of the pitting was about 1.5mm deep on ours! Could it be that the same has happened on yours and the pitting had worked all the way through the full 3mm? Let's hope not, but that's the first potential failure.
On ours, it was clear that there had previously been a leak from the rubber fuel hose leading to the engine. In fact, the old perished rubber hose was still in there, cable tied to all the wiring running aft, with new hose alongside. It may be that this hose has reached the end of its life in yours and has finally cracked/started to leak.
Furthermore, the fuel hose was never really all that well supported along its whole run back to the engine compartment. Therefore I wouldn't be surprised if it has failed elsewhere along its length.
When the new hose was fitted to ours, the fuel shutoff valve (accessed in the little storage cut-out beside the helm position) was completely bypassed. I've seen a few of the same boat without this fitted, but if yours has this, then that is another (unlikely) leaky component.
Refitting is fairly easy - but allow a good few cartridges of a decent adhesive sealant to seal around the underside of the deck sole! FOr the screws, I'm sure just A4 stainless nylock nuts and penny washers was be OK (proiding they weren't over tightened - as the backsides of the holes go through a step-shaped moulding, so there's no flat surface to fasten onto). On ours, I made up some close fitting ply open-topped 'boxes' that had the contour of the underside surface cut into the top. These were held in place with sikaflex, and I syringed toughened epoxy through the screw's clearance hole. Once this had gone off, I drilled and tapped these holes, and had a really good, corrosion-proof blind fastening system that appears to have worked well!
One thing you might do it just sniff about under the round fuel sender access hatch and see if the fumes smell any stronger under there.
I'm sure this goes without saying, but obviously, if it does turn out to be a leak steer clear from using anything sparky when removing the deck sole! No electric drills or the like!
Let's hope it is just fuel vapours coming from the carb!
Sorry for the long one, but hope that helps