Brand New Fuel tank, but smell fuel in cabin

[spoons]

Ok guys... I just got done restoring a 20' 1984 Grady Overnighter with a I/O motor.

I replaced the fuel tank on the boat this past summer with a brand new one from the original manufacturer in Florida. It came with a new sending unit and I replaced the fuel fill lines as well as the vent line as well as the feed line. I used a fuel rated hose on the feed line and the fuel fill line but NOT on the vent line (I wasn't thinking).

Anyway, fast forward through an engine repower, outdrive rebuild and I finally get to plumbing the new tank. I put it all together and button down the deck hatch and seal it. It's a 65 gallon tank and I initially filled it with 25 gallons of fuel just to get the engine fired up. I get the engine all fired up and a go for a short sea trial, never a smell of fuel.

Fast forward again another week later. I want to get the boat fully loaded and go for a couple hour sea trial so I fill the boat all the way up....that's where it started. I put 40 gallons in her to top her off. I launch the boat and get it all fired up and start going for a cruise. The engine compartment doesn't smell of fuel, the inspection plate for the fuel tank smells a TINY little bit, but the strongest fuel smell is really coming from inside the cuddy cabin.

Question here is.....is the vapors leaking through the non fuel rated vent line that I put in or do I have a crack in my brand new fuel tank?

It's raining right now otherwise i'd open up the fuel deck hatch completely to find out but I wanted to see what your guys' thoughts were.

On a side note, this boat is great, 21-22 kt cruise at 3500 rpm (with a 3.8 omc/gm v6) and 30 knts wfo.

 

[Pez Vela]

Question here is.....is the vapors leaking through the non fuel rated vent line that I put in or do I have a crack in my brand new fuel tank?

Probably neither, but the strong odor in the cabin is a very bad sign (from my personal experience). What I do know is this: it will stop raining eventually, and then you'll find out. My guess is that the sending unit gasket is leaking and that by topping off, you've found the weakest link.

 

[SmokyMtnGrady]

Replacing a fuel tank involved plumbing. I hate plumbing. I would pull the hatch as well and inpsect all the hoses and the gasket like the Pez says around the sending unit. Then again I think you know this to be true. Then while you are at to make sure the vent hose is rated for petrol, replace it as well. The issue, as you likely know too, is gasoline is also a solvent and hoses not rated for that kind of use will gumm up and eventually fail. The vent hose is likely not going to fail tomorrow, but over time it may slowly gum up and then voila it is gone. You go to fill the tank and one day fuel vents into the bilge. Good luck in your search.

 

[Lt.Mike]

Could it be leaking from around the spin on fuel filter ?
You may have done nothing with it and it just timed this moment to leak to make a simple problem more confusing.

 

[spoons]

Brand new spin on fuel filter/water separator. Brand new fuel pump, no leaks at either location. No leaks around carburetor either.

I'll check back after I lift the hatch. Gonna be out of pocket for a few days, but i'll do it as soon as I get back.

 

[wrxhoon]

I think I have to agree with Pez Vela, the first thing to check is the fuel sender gasket.
If you can't find what it is pump some compressed air, low pressure ( only need 5 psi) via a regulator and you will find for sure . The reason the cabin smells is because it's closed and all the vapor stays there, it probably goes in there from the bilge under the tank. Make sure all the hoses you used are rated for fuel and don't use ethanol blended fuel.

 

[bayrat]

All good ideas have been given but don't discount the possibility of a defective tank (welds where fill, vent hoses are attached etc). Open the hatches, air out the cabin and bilge and then let your nose be your guide. Get as close as possible to the tank and, where you can't reach, use a length of rubber hose to sniff suspect areas.

 

[BobP]

Look at the bilge water at the stern, is there a rainbow on the water?

Where is the fill deck fitting and vent on that model ?

When you filled the tank, did any liquid push back up the fill or out the vent down to the water over the side?

I'm sure you wrote with the new tank all new hoses and clamps too.

 

[GW VOYAGER]

I had my sending units replaced with new motor and no gas smell for about a year. last time if filled I did get an odor of gas. I pulled an inspection plate and the gasket on the sending unit was leaking. I cleaned the spilled fuel and tightened the sending unit and no more leak. Good luck!