Fuek tank vent/overflow problem

[SeaEric]

I own a 1966 Hatteras 41 TC powered with 8v53's. Two fiberglass fuel tanks are under the aft berths. Fuel fill pipes go pretty much straight in from the corners of the aft deck, down into the aft corners of the tanks. Fuel gauges are working and indicate that the tanks are about 1/4 full. Beginning at the last time I fueled the boat, the port tank spits diesel fuel out of the vent/overflow when I try to fuel that tank, as if it's near full which it is not. No problem with fueling the stbd tank. Before I dig into this, does anyone have any idea what may be going on? It seems not to matter how slowly I run the nozzle.

 

[jim rosenthal]

Notwithstanding that the fuel gauges say that the tanks are 1/4 full, have you dipped the tanks to make certain? And are the valves set so that fuel coming from any given tank to an engine goes back to the same tank? Otherwise you may be returning fuel from both engines to one tank. Which may in fact be full.

If you are certain beyond doubt that each engine is drawing from its respective tank and returning to that same tank, and that fuel is not mixing from one side to the other, then perhaps the vent to the tank on the side that's spitting up is clogged and air isn't able to exit the tank when you are fueling.

If you determine the boat is spitting up, you can try feeding the boat slowly and then holding the boat to your chest after she's done feeding, patting her on the hardtop. Some soothing music may help. You can also think about changing the formula- maybe a different brand of diesel fuel might help.

If you think your boat is choking or vomiting, then try holding the boat upside down and firmly patting her on the back.

If all those measure fail, you may have a colicky boat. In that case, she may benefit from a ride in the car. Just bundle her up in the back seat- make sure to use a certified car seat- and take her for a ride. About twenty minutes or so should do it. Then, carefully, without waking her, put her back in her slip. Don't forget to hook up the shore power cord.

 

[Freeebird]

I am SO glad you left the ER in Quincy.

 

[rsmith]

There is a dip in the vent line that's holding fuel from the last fill

 

[rwappleton]

I think Mr Smith is correct However Jim's remedy's are really funny and I can see Randy hiding his hand which is extra funny!

On your boat I do not think those vent lines are that hard to get to. Or not as hard as you might be thinking. OTOH Jim might be on to something too.......................................................................The colic I mean

 

[Boatsb]

Pull the vent hose off the tank end and see if its clear. Suction is a bad idea as it will lodge the obstruction deeper. I have had to rod out nests of mud daubers and dirt before. Pull the vent side too and good luck squeezing in there between the transom and the master bulkhead. Its made for flexible skinny guys.

 

[MikeP]

I feel strongly both ways!

Tank could be full and gauge wrong.

As Jim said, can you dip the tank to be sure of the level? On our 53 the tank has a couple of small NPT fittings on top that are accessible from above. If yours is the same you could remove one of those fittings and stick an appropriate size dowel in to check the level. If it's totally full, you're done!

OR

Vent could have a "U" that has fuel in it.

You could blow some compressed air, set at fairly low pressure with the nozzle sealed to the vent with a plastic bag or whatever, into the fuel vent with the filler cap for the tank removed. You should be able to hear if it clears any fuel in the vent and, if the tank is truly overfull (and you couldn't get access to dip it), you'll hear it bubbling.

 

[SeaEric]

Since my boat (luckily) doesn't qualify for Obamacare, I will probably solve this malady by calling my mechanic. On the phone now.

 

[SeaEric]

To be clear, this is not a boat that I met at a bar last night in a drunken stupor. If it was, and she was belching diesel all over my environment I'd give her a cup of coffee in a Styrofoam cup and walk her to the door. No, I have a long term committed, loving relationship with this boat. I have run quite a few hours this Summer and have only fueled three times. First fueling of the season was uneventful. Second and third visits to the fuel dock I only got about 20 gal in the port tank before diesel was coming out of the vent. I never fill my tanks to the top. No valves have been turned or changed. If one tank was full and the other was 1/4 full, the boat would be listing. It's not. Unless there is a diesel refinery and a source of crude (besides this forum) in the lazarrette, the tank is not overfull. The vent is obviously not clogged as a stream of raw fuel pours out when I try to add fuel to the tank.

 

[rwappleton]

We are waiting for the results with Diesel baited breath

 

[Freeebird]

Somebody stuff a tampon in your fuel fill? A banana maybe?

 

[SeaEric]

Most serious threads on this forum go off the rails at some point.
It's really discouraging when it happens in post #2.

 

[jim rosenthal]

Well, the FIRST part of the post was serious. I don't know what happened to me after that. When the fog cleared, there was all this foolishness right there in the thread and I had no recollection of it. I must have done it, but I don't remember. I apologize profusely. I can't think what came over me.

 

[jim rosenthal]

All attempts (!) at humor aside, it does sound like the vent line is blocked. I wonder why now, though, if you didn't have trouble fueling the boat before now. Weird.

 

[Canuck Dennis]

How can the vent be blocked if fuel comes out from the tank when filling ??, is it possible that the vents are crossed ?

 

[MikeP]

A pair of shadowy figures skulk about in the dead of night armed with a corroded hand pump and some bedraggled hose. There's a slithering sound of the hoses being snaked into the two fuel fittings followed by the "whup, whup, whup" of the pump and the faint gurgle as they impel fuel from one tank into the other. They ensure one tank is full and then, eyes gleaming in demonic mirth, they cackle maniacally over their jest and disappear, footsteps padding wetly into the darkness.

Or maybe it's just a clogged vent...

maybe...

 

[SeaEric]

How can the vent be blocked if fuel comes out from the tank when filling ??

What Dennis said....

 

[Freeebird]

How can the vent be blocked if fuel comes out from the tank when filling ??, is it possible that the vents are crossed ?

Then it would vent to the other side.

This isn't rocket science. Fuel goes into the tank through one hose and vents out another. Check them both for blockage. I'm assuming you have the same amount of work room on your TC as I do on my DC. Should be a piece of cake.

 

[SeaEric]

Luckily, I'm a rich, white republican. Unlike our government - this is a problem that CAN actually be solved if I throw enough money at it.

 

[jim rosenthal]

I didn't read the original post carefully enough. What I THOUGHT you meant was that when you tried to fuel the boat, fuel came back up through the main fuel inlet. That's why I thought the vent tube was clogged. But that is not, in fact, what you said.

The only thing I can think of is that fuel IS getting into a low spot in the vent tube and hanging out there, and then being pushed out by air escaping from the tank as it fills. I suppose the way to figure that out would be to either look at the vent tube, if that's possible, or provide another way for air to escape the tank and then try fueling the boat again.

It's all very odd. I no longer think your boat has colic. I stand corrected.