How to debug a fuel smell problem

[pvancorenland]

I have a VP 5.7L GSIPEFS engine, which has Throttle Body Injection.
I keep it covered under a very tight waterproof, but "breathable" cover. When I open the cover after about 2 weeks, I get a fairly strong smell of gas that doesn't necessarily get stronger when opening the engine cover.
How do I go about figuring out where the smell comes from? all fuel lines seem tight, my Fuel filter is on tight, the smell doesn't come from the gas tank vent hole since that's not covered, so what do I try.
The boat is a '02 226 cobalt

 

[pvancorenland]

Re: How to debug a fuel smell problem

After some more investigation, it does not seem to be a bilge problem. The smell is present under the (very tight) cover, but not in the bilge (as far as I can tell).
I did find a big stain on my asphalt right underneath the gas tank vent. The stain is pretty large and smells like fuel. Right underneath the vent, there is a spot (size of a glove) where the asphalt has been eaten away. See the picture below. There is a vague fuel smell present in the lockers through which the vent line runs.

Before I winterized the boat, I filled the tank completely and stored the boat with the bow up as much as possible. When I opened the gas cap just now, it was sucking some air, so the gas tank seems to hold. The engine was used only minimally after filling the tank (for fogging 4 months ago)

From the fuel stains, it seems that the fuel vent has been spilling. What could have caused this?

The boat is an '02 Cobalt 226 which has a plastic fuel tank (from the looks of it).

 

[Don S]

Re: How to debug a fuel smell problem

From the fuel stains, it seems that the fuel vent has been spilling. What could have caused this?

Full tank,l expanding fuel when it gets warm, the bow being high probably had some to do with it depending on where the vent is located on the tank, and out the vent it goes.
Your canvas may be breathable, but it really needs some through flow ventilation.

 

[pvancorenland]

Re: How to debug a fuel smell problem

Don,

I understand the fuel expanding part, but my vent is not covered by the cover, so I'm wondering why the smell got under the cover and how a high bow could make this worse (from the look of it, the gas tank is between the upper bow and the stern, so lifting the bow high would not put liquid pressure on the vent, but then again, the tank was full.

Should I be concerned?
I plan to put the bow down as much as possible, and put the cover on tight the same way as before and see if it makes a difference.

 

[riptorn]

Re: How to debug a fuel smell problem

Is is ok to store a boat during the winter with a full tank of gas? I thought this was a no no?

 

[spoilsofwar]

Re: How to debug a fuel smell problem

Is is ok to store a boat during the winter with a full tank of gas? I thought this was a no no?

Assuming the fuel in question contains ethanol, its recommended.