Gass fumes mercruiser 5.0l

[Dutchlarson]

Hi all,

A few weeks ago i bought a 2004 Mariah SX22 with a 5.0l Mercruiser. Its a well maintained boat, and i have a lot of faith that it will bring a lot of joy to the coming summer.

However every time i open the cover there is a pretty strong gass smell. This is my 4th boat so i know you always smell a little bit gass because of the open carb, however this is very strong.

I checked all the gass lines, and the sender, but everything seems ok and i see no leakage.

Anybody have an idea or tips where this could come from?

 

[Scott Danforth]

gas vapors are strong and dense and will settle to the bilge, hence why you smell it. find the source of your leak.and do not use the boat until you do

check your vent tube. if you have a leak most of the time you wont see it, as its just enough to release vapor. raw gas is bad, vapor is explosive

 

[Bondo]

Ayuh,.... It could be anything from the tank itself to the carb,...

Everything is Suspect,....

 

[alldodge]

Check the fill tank hose, vent hose, charcoal canister (might have one).
If you tank is full and the weather getting warmer, expansion of the gas will start filling up the hose and everything else and build a tad bit of pressure

 

[Dutchlarson]

But how do i check these tubes other than visually? I have been looking for over an hour with a strong led light, and felt every area with my fingers and everything feels dry.

I have no idea where to look anymore

 

[alldodge]

If you have a plastic tank this can cause somewhat of an issue. Plastic tanks are permeable, so the smell comes thru the plastic. Only issue is you said it was "pretty strong"

 

[flipbro]

Check were your gas gauge sending unit goes in tank.

 

[Dutchlarson]

Checked this sending unit. Looks and feels good. Screws are in tight and the gasket seems good.

Dont know where or how to look any further...

 

[alldodge]

I don't have any other ideas, your boat being a 2004 would have ethanol resistive hose. Some of the older boats without the newer hose would dry rot and crack apart over time.

Didn't notice where you mentioned what your tank is made out of. If its aluminum, water can eat thru it from the outside over time if the hull.

 

[Dutchlarson]

The tank is plastic.

the hoses seem all fine. I am not a technician ohterwise i wouldnt ask you guys for help, however i worked at a gasket/sealing/rubber company for 8 years so with some common sense i can see that the hoses and gaskets are all in good condition. No cracks, no moist or signs of leakage, and they all just look and feel good.