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Fuel Smell, Leak?

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Hello Everyone,

I have just become part of the Malibu family with the purchase of a 99 Response after a 20 year absence from boating. The boat only has 303 hours but is due for a complete tuneup and good maintenance run through. This is my first inboard direct drive and i have a strong fuel smell in the rear hatch that i can not seen to track down. After completing the rubies' cube and getting the cover off the fuel tank it did not reveal much. The smell is not coming from the breather and is still noticeable even when the hatch has been open for a long period of time. I am open to suggestions on what to be looking for before pulling the tank.


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The vent tube and fuel filler tube secure would be where I look first.  Then the gas line going to the engine.  If ethanol (kind of hard to avoid in most locations now) has been used, the fuel line maybe breaking down and letting vapors escape - probably along with some fuel.  I don't smell gas in the trunk of my '99.

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Since you have been away from boating for 20 years, and I'm gonna assume your engine is fuel injected, I'm just gonna say you simply must fix this problem prior to turning the key in your boat again.  You should never smell fuel in the bilge or any other closed compartment or anywhere else for that matter in a fuel injected boat.  It's not something your blower can rectify.  Not like the old days of carb'd boats where you would have the smell of fuel from the float bowl and rely on the blower to evacuate those fumes prior to start.

Find the problem before you run the boat.

If you know all this stuff, then my apologies, but just wanted to make sure you are aware of the seriousness of a fuel smell issue....especially if your engine is a Monsoon.

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Thanks for all the suggestions. I have not found a smoking gun yet but all the fuel lines are showing there age and will be replaced. Both fuel filters seem to be in tact with no apparent leaks. The engine compartment and carpet in the rear hatch were very dirty with a black film. I found the breather hose pulled out of the valve cover and am not sure if that would cause this if it was out for a long time. I am beginning to think the smell is just permiating from the soot. I will steam clean and see if that solves it. Going to pull the tank anyway since I am this far and replace the blower hoses that look like a failure waiting to happen.

One more question, is the check valve on the breather line a maintanance item or is there a way to check if it is working properly? Does it open under pressure or is it just a valve to prevent water from getting in?

thanks for the help

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My 96 vlx efi always has smelled of fuel in hatch.  I have new fill hoses and have fixed any leaking fittings and hoses etc.  It is always possible there's a pin hole in my tank but the fuel level doesn't change. I've read articles online (I believe everything I read on Internet) and some suggest that some types of older plastic tanks breath and it's impossible to eliminate the smell.    I've been leaning on that theory in my boat.  The fittings on the bracket of my fuel pump return  was leaking at one point I recommend you take a good look in that area.

Edited by Shastasurf
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  • 3 weeks later...

@Tver:  I believe the valve you are referring to which should be the one on the fuel tank vent line mounted on the fuel tank, is the anti siphon valve.  Yes, you will want to check it over as they can stick.  I have seen them stick and create a vacuum issue in the tank which causes the engine to run poorly.  While the tank if off, remove and check/inspect/clean the valve (or replace if corroded), it is a simple ball/spring check valve.  The soot you are referring to may be primarily from the crankcase vent line not being connected, although over a long period of time the transom area will accumulate grime from any excessive blow by or fluid weeps / leaks, etc.

Welcome to the Bu family, your vessel should provide many years of excellent boating activities and fun family times.  That an a relatively constant drain on the family finances as you accumulate more toys to enjoy behind your new purchase!

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