Osprey Vipermax fuel tank breather issue

[Anchorhandler]

Hey all

Just came back home to be greeted by a very strong smell of fuel eminating from Gwenn....

On inspection, was amazed to see petrol quite literally being pumped up and out through the fuel tank breather outlet just above the main filling point. I'm not talking drops either, it was a constant flow witht the stream about 4-5mm in diameter .

I suspect that due to the angle that Gwenn is currently sitting at (we live on a hill but not what i would call excessive anyway, see picture) the breather pipe must connect to the main tank somewhere towards the rear of the tank itself. The tank has oviously warmed up considerably during the day due that elusive ball of fire in the sky beating down on the dark coloured deck and created a vapor pressure in the forward part of the tank causing the fuel to be 'pumped' up and out. Quite something to see.

Had to rush to the garden hose and wash her down rather sharpish before opening the main filler plug to relieve the pressure.

Can anyone confirm if the breather pipe does actually connect to the main fuel tank at its rearmost part? The tank was about 60% full at the time.

I'm scared to look to see what the guage is now reading...


The third picture is nothing to do with the petrol leaking but makes me chuckle...I took it yesterday going through the lock at the hydro-electric dam in St Malo (Barrage de la Rance)...... i call it a WAFI jam

Simon

[bedajim]

Originally Posted by Anchorhandler

Hey all

Just came back home to be greeted by a very strong smell of fuel eminating from Gwenn....

On inspection, was amazed to see petrol quite literally being pumped up and out through the fuel tank breather outlet just above the main filling point. I'm not talking drops either, it was a constant flow witht the stream about 4-5mm in diameter .

I suspect that due to the angle that Gwenn is currently sitting at (we live on a hill but not what i would call excessive anyway, see picture) the breather pipe must connect to the main tank somewhere towards the rear of the tank itself. The tank has oviously warmed up considerably during the day due that elusive ball of fire in the sky beating down on the dark coloured deck and created a vapor pressure in the forward part of the tank causing the fuel to be 'pumped' up and out. Quite something to see.

Had to rush to the garden hose and wash her down rather sharpish before opening the main filler plug to relieve the pressure.

Can anyone confirm if the breather pipe does actually connect to the main fuel tank at its rearmost part? The tank was about 60% full at the time.

I'm scared to look to see what the guage is now reading...


The third picture is nothing to do with the petrol leaking but makes me chuckle...I took it yesterday going through the lock at the hydro-electric dam in St Malo (Barrage de la Rance)...... i call it a WAFI jam

Simon

I never had that happen, but did have a little petrol come out if you filled the tank to the absolute brim including the filler pipe.

Never had sun like this either

Jim

[Silverfox]

I have a viper max too, and never had that happen. But I do know that the breather pipe has a kink in it, and when filling it can serge back, rather like drinking a yard of ale . But never when left alone.

[Anchorhandler]

Hi Jim/Will

Do you guys know where the breather pipe connects to the fuel tank though?

Its the only possible explanation i have for it happening.....one of those "rub your eyes in disbelief" moments.

It was actually my wallet that allerted me the problem. it started having spasms in my back pocket long before i got near 'sniffing' distance of the boat...

Simon

[Nos4r2]

For now, it's probably worth just leaving the fuel filler slightly unscrewed while on the driveway.

[Silverfox]

Originally Posted by Anchorhandler

Hi Jim/Will

Do you guys know where the breather pipe connects to the fuel tank though?

Its the only possible explanation i have for it happening.....one of those "rub your eyes in disbelief" moments.

It was actually my wallet that allerted me the problem. it started having spasms in my back pocket long before i got near 'sniffing' distance of the boat...

Simon

I thought I had a photo, but I don't, and sorry I can't remember off the top of my head. I'll keep looking though.

[Silverfox]

Originally Posted by Anchorhandler

Hi Jim/Will

Do you guys know where the breather pipe connects to the fuel tank though?

Its the only possible explanation i have for it happening.....one of those "rub your eyes in disbelief" moments.

It was actually my wallet that allerted me the problem. it started having spasms in my back pocket long before i got near 'sniffing' distance of the boat...

Simon

Isn't it something like this? New Boatbuilders Home Page - Fuel Tank Setup Diagram

[Anchorhandler]

Originally Posted by Nos4r2

For now, it's probably worth just leaving the fuel filler slightly unscrewed while on the driveway.

Hi Nos4r2

Thats exactly what I've done for now... Pretty surreal as i originally shut the filler cap after 20minutes or so and sure enough within a few minutes it started pissing out again.....

Thanks Silverfox, thats a handy diagram. I recon it must be similar (but without the carbon filter).

To lift the petrol up to the height of the breather outlet requires energy.... The only way i can see possible to gain that energy is by heating the tank up ( through the sun) but it would mean the breather pipe entrance at the tank would need to be submerged.....
If the tank was full i could understand but as i mentioned we had used Gwenn most of the day yesterday and had but filled her up afterwards.

Bit of a strange (and worrying ) one.

Cheers for the help though guys

Simon

[Erin]

As far as I know the fuel fill and breather points are mounted on a slightly raised section about 1/3 from the front. Unless your breather pipe projects below the top of the tank and dips into the fuel I struggle to see how your problem has happened, especially if it was only 60% full. I have a picture somewhere which I will post later.

[Mollers]

Originally Posted by bedajim

, but did have a little petrol come out....
Jim

Enough to create a rainbow slick stretching from Lands End to the Scillies.

[1978SeaRider]

I've had it on my osprey... I put it down to overfilling then moving her, as the fuel rocked back and forth it squirted out. I had to get a pint glass and kitchen roll to stop my tubes getting coated.

I would imagine yours is a combination of storage angle and heat.. Maybe the vent pipe's a bit long and dips into the tank at that angle too ?... Although not sure of the exact set up in the tank

[Erin]

Not sure if this helps. It was a photo that hightower posted some time ago. Shows that my memory is not as good as I thought as the raised connection points are 1/3 from the back not the front.

[Anchorhandler]

Originally Posted by Erin

Not sure if this helps. It was a photo that hightower posted some time ago. Shows that my memory is not as good as I thought as the raised connection points are 1/3 from the back not the front.

Hi Keith
Yes, thanks for re-posting the pic, it does confirm my suspicions. Shame there is no forward breather as most ribs will sit with a stern trim.

Looking at the pic im quite confident that thats what happened, a void has been created in the fwd part of the tank as the fuel has naturally ran aft sealing off the void from the breather.
As the tank has warmed up it has gradually pushed the fuel out of the tank.

I suppose its something that maybe other Vipermax owners should not necessarily worry about but be aware of anyway.

Thanks again guys for the help in confirming this.

Simon

[Hightower]

Ah yes, that's a picture of my tank!

After nearly 5 years of ownership I had this exact thing happen only this year, when I brim the tank I usually use a fair bit before I recover for the day. This particular day I brimmed the tank but only used the RIB to cruise out to a local fishing mark, so used less than 20l. I recovered and put the RIB to bed, up the drive as usual.

We had a spot of warmer weather a couple of days later and guess what, fuel all over the floor of the console. When I stuck my head in to have a look I could see the fuel level in the clear breather hose, but instead of coming out the breather to exit outside the console the fuel had found a gap in an ill fitting breather hose and dibbled into the console. After I had soaked up the petrol with some rags I calculated that a good few liters had come out.

So it looks like a common problem that can be solved by either not storing the RIB with a full tank or lowering the front of the trailer so that the trapped air can vent. This latter solution obviously means that during storage rain will run towards that bow instead of coming out the elephants trunk.

Here's a couple of different views:

[BogMonster]

I've had problems with fuel getting into the underseat compartment on mine when it's full (single dive console with the tank outlet under the seat). It doesn't leak visibly but when the boat is left with the tank topped right off, it dumps a wee bit under the seat, maybe a couple of tablespoonfuls. I assume it's something to do with the breather too, but I can't figure out where it is escaping. Let the level drop a bit and the problem disappears, so I now just top it off to about 5L short. I guess it's a similar expansion problem and maybe the connection on the breather isn't tight but it's a bugger to get to so I haven't worried about it too much. Another job for the winter

[mitchc]

I was having exactly the same problem. The filler is at the front of the tank, with the vent at the rear. Its now reconfigured with a remote filler in the console and the rear vent blocked off. The vent is braised into the brass filler fitting in the top of the tank. I can now fill with no problems and get no spit back through the vent.
Photos of before and after the console was moved. The filler was originally under the deck plate in the first photo.

[Ian M]

Originally Posted by Hightower

So it looks like a common problem that can be solved by------lowering the front of the trailer so that the trapped air can vent. This latter solution obviously means that during storage rain will run towards that bow instead of coming out the elephants trunk.

Been away in Greece, so only just caught up with this thread. I have had the usual problem of fuel coming back up the breather when filling and a little when the boat gets really hot and the tank is full, but nothing on the scale described by Anchorhandler ---- but my boat is always stored bow down. So I guess Andy is right