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Author Topic:   305 CONQUEST Serious Fuel Leak
Barrykrocker posted 02-28-2008 01:55 AM ET (US)   Profile for Barrykrocker   Send Email to Barrykrocker  
We went onboard [2005 Boston Whaler 305 CONQUEST]. We hadn't been on for a month or so. The cabin stank of petrol, but we weren't too alarmed because this had happened when we first took delivery of the boat and filled all the tanks to capacity, which we had done again the previous time we finished using it. We naturally assumed it was a petrol overfill, and the fumes would pass like the first time it happened.

We got underway and had gone through some swell, and within half an hour the carbon monoxide alarm went off. The cabin has an extreme odor of fumes.

We took [the 2005 Boston Whaler 305 CONQUEST] back, opened all the port holes, and successfully aired it out a bit. Then we plugged in shore power and put on the air conditioner which made the fumes much worse. We checked the forward bilge under the cabin floor AND IT WAS [literally] FULL OF PETROL. We eventually got [the petrol] all out by scooping it into buckets rather than putting the bilge pump on). There was about 10-litres of it.

Thinking this might still be the effects of petrol overflow from filling the tanks to capacity (which a general boat mechanic agreed with), we left the boat to see if the forward bilge would fill up with petrol any further whilst the boat was docked. This was two weeks ago and we just got word from the mechanic that there was indeed another couple of cup-fulls of petrol in it. He said that this could just be additional petrol from the overflow that had finally drained down but I'm thinking this could be much more serious.

Just talked to Boston Whaler and they said it sounded pretty bad. The 305 is in a different town (200-KM away) where there's no Boston Whaler dealership. We are going to have to get a Boston Whaler mechanic get up there for a look.

Any thoughts as to what could have happened in the mean time?


Brian7son posted 02-28-2008 08:45 AM ET (US)     Profile for Brian7son  Send Email to Brian7son     

You should be able to fill your tanks without any issues of fumes or fuel overflowing into your bilge. If you had that problem when you took delivery, Whaler should have diagnosed it then.

Just a wild guess, but it sounds like you have a leak (a small hole or crack) on the top section of one of your fuel tanks. When you top it off, it leaks out until the fuel level is below the leak.

As you stated, this is a very "serious" problem. Personally, I would not operate that boat until B.W. sends a representative to inspect and diagnose the problem. With all of those fumes in the cabin, simply flipping a breaker could potentially cause an explosion. It is very dangerous.

Good luck with your problem,


P.S. Just a suggestion, when fueling up, I wouldnt necessarily "top if off" all the way up so that fuel is all the way up to the gas cap. Personally, I like to leave a little room, maybe fill up to 9/10's of a tank or just "slightly" under full.

jimh posted 02-28-2008 08:48 AM ET (US)     Profile for jimh  Send Email to jimh     
My speculation is that there is a leak in the filler hose. When you fill the fuel tank to the brim, you often leave fuel in the filler hose. It is possible that there is some permeability in the filler hose which is not so bad that it leaks during the filling process, but if fuel is left standing in the filler hose, the permeability may be enough to let fuel get out.

Also, with a full tank and operating the boat "in some swell" there may have been some surging of the fuel in the tank. This might have produced some pressure on the filler hose and burst it.

And, there may be a poor seal in the upper part of the tank which leaks only in the circumstance of a very full tank.

I believe the fuel tank on the 305 CONQUEST is aluminum. Is that correct for your model?

jollyrog305 posted 02-28-2008 12:41 PM ET (US)     Profile for jollyrog305    
I would check the fittings and sender on the auxiliary tank which is located directly behind the forward bilge area. Also, Boston Whaler recommends that the fuel tanks should never be filled to capacity - allow 2% for expansion.
Buckda posted 02-28-2008 08:02 PM ET (US)     Profile for Buckda  Send Email to Buckda     
Possibly a SS hose clamp is loose on the filler or delivery hose. With a full tank, this could allow for some fuel to seep out, especially under pressure of expansion or in sea swells.

Definitely disconnect the shore power and remove the batteries until this is solved. Those fumes are explosive.

Ricky posted 03-01-2008 03:11 PM ET (US)     Profile for Ricky  Send Email to Ricky     
This is beyond serious in my view. You could be blown sky high. This boat has up to 300 gallons of gas. Seems this is a job for Whaler rep or experienced yard. I wouldn't step foot on that boat until the problem is found and fixed. Good grief.

As a 305 owner, same year, I am quite anxious to hear what the problem is so I can have mine checked. I hope you post your findings.

Whaler dealer just installed solenoid valves on my boat at or close to the tanks to prevent siphoning into Verados or so I was told. This was a Whaler recall fully paid for by Whaler. Maybe related??

jollyrog305 posted 03-01-2008 05:52 PM ET (US)     Profile for jollyrog305    

Was that recall on 05's only? Have an 06 and want to make sure I have it looked at if necessary (never got anything in the mail from BW).

Barrykrocker ,

I agree with Buckda - remove all power/sources of ignition immediately. I would see if I could remove 5-10 gallons of fuel from each of the tanks (manually of course), especially from the aux. I would wait a week and see if the problem still occurs (still not power to the boat). I would then check the fittings around the hoses and see/track any staining/trails back to the source of the leak.

I still believe that filling the tanks to capacity is the cause of the problem, based on that this has happened only two times - each after filling the tanks to capacity. When you took the boat out and started smelling the fumes after 30 minutes - were you running off the port and starboard tanks (i.e. not the aux)? Were you out long enough to even burn any fuel from the tanks? However, I wonder if (over) filling the tank the first time, resulted in/caused additonal damage to an existing problem. Get a qualified mechanic (even if you have to pay for his/their travel time) to look at the problem - I think everyone agrees - this is VERY serious.

handn posted 03-01-2008 08:57 PM ET (US)     Profile for handn  Send Email to handn     
I agree with everyone that this is a very serious problem. I wouldn't run the boat, plug in shore power, or even turn on the 12 volt system. I would leave the bilges open so vapors can disapate.
Fortunately leaking fuel leaves evidence in the form of discoloration where the leak has occured. There are various hatches and round covers that can be pulled off to inspect the plumbing of the system.
It has been my experience that Boston Whaler has been very responsive about customer service. Regardless of whether the boat is in or out of warranty, they should be very responsive to help you to correct a huge safety issue.
If it were my boat, I wouldn't start it and put it on a trailer and take it to a distant dealer. Doing so without repair of the cause of the problem is unsafe.
Since everyone else is guessing about the source of the leak, I add mine. My guess is one of the fuel vents is defective. After fueling, my 305 emits strong vapors from the vents when the boat is run and fuel sloshes around in the tank. When a little fuel is used, the smells go away. If a vent is plugged or defective, the fuel is put under pressure when sloshed around and leaks out somewhere.
I think under fueling by a little bit is a good idea. I don't like to smell gasoline and it is irresponsible to let it leak into the atmosphere.
I am sure your problem will be diagnosed and solved quickly. Leaking fuel is like an escaped elephant. Let is forum members know so we can check our 305's
Ricky posted 03-02-2008 09:18 AM ET (US)     Profile for Ricky  Send Email to Ricky     
Jollyrog305- not sure about recall. My dealer informed me about it. Never received anything in the mail. Check with dealer.
jollyrog305 posted 03-02-2008 09:35 AM ET (US)     Profile for jollyrog305    
Thanks Ricky - will send the local Service Dept an e-mail
boatdryver posted 03-02-2008 10:47 AM ET (US)     Profile for boatdryver  Send Email to boatdryver     
I wish Barrykrocker would give us a followup!


kenv posted 03-06-2008 12:49 AM ET (US)     Profile for kenv  Send Email to kenv     
I believe there is some type of fuel tank recall on the Outrage 320. Not sure if this helps you. My dad got a letter in the mail last week regarding the clamps/crimps being too tight and causing the fuel lines to break. The dealer had not received notification until my dad showed them the letter. They knew nothing about it. I would check directly with whaler. He has an '07. Not sure if this would go back to '05 but you never know.


JIGS posted 03-09-2008 10:53 PM ET (US)     Profile for JIGS  Send Email to JIGS     
I had a very similar issue with my 2005: 305 Conquest. The cause was a leaking gasket on top of the aux tank. The location of the leak and the repair was easy but not obvious, because it was covered up. Once I opened the round hatch underneath the rear berth mattress, it became very apparent what was causing the strong odor of gas after a fill-up. The dealer replaced the gasket and I haven’t had a problem hence. In addition to checking the aux tank you should look at the port tank via the access hatch next to rear berth light, even though a visual inspection of the port tank is not available you can still feel around the gasket and smell your fingers for signs of gas leaks. The access to the starboard tank is more complicated as you have to take out the fire extinguisher housing next to the helm for better access.

As previously stated, dont use the boat until this problem is fully fixed.

Ricky posted 04-05-2008 10:13 AM ET (US)     Profile for Ricky  Send Email to Ricky     
Sure would like to know how this was resolved. Maybe power of suggestion, but I think I am smelling fumes now also.(I have 05 Conquest as well) But no liqiuid anywhere. Was thinking maybe station wagon effect but not noticeable when tanks are drawn down.

Think I will take to dealer but would be helpful to relate this story and resolution.

jimh posted 04-09-2008 09:21 AM ET (US)     Profile for jimh  Send Email to jimh     
I sent email to Errol seeking an update. The problem has not been resolved yet.

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