Vents leaking

Beflyguy · Posted: Tue Jun 01, 2010 9:48 pm Post subject: Vents leaking

I searched the site but didn't find a description of this particular problem.

I first noticed that when filling up the Tomcat, that fuel would start squirting out the vents before the nozzle auto-shutoff and before the fuel got to the top of the filler. Now, after using a few gallons of fuel last Sunday, the boat is sitting in the driveway and fuel is seeping out both vents enough to run down the rub rail and drip off the back of the boat. It is a little by the stern as it sits but the problem didn't come up until the weather started warming a bit. If there is serious work needed, I will have to take it back to Master Marine but I wonder what is normal and what can be done.

I looked at the tank fittings on both sides but I'm not sure where the problem lies.

localboy · Posted: Tue Jun 01, 2010 9:55 pm Post subject:

Brian, the gas will expand as the weather heats up. Fill it TOO much, and it will slowly leak out the vents. As far as filling it and having it "spurt" out the vents, that happens too. I usually stand in the boat and control the filler by hand, listening as the fuel fills the tank. Sometimes you can hear it filling the vent tube and stop before it spurts out. By then your tank is pretty much topped off. You don't want fuel in the fill tubes or the vent tubes or you'll be back to problem #1 when it warms up.

Captains Cat · Posted: Tue Jun 01, 2010 10:03 pm Post subject:

I have the same problem with my TC. And my fuel tank gages are inaccurate. Read empty when they are half full. I tried to find fuel flow meters for my suzi 115's but they will not work on the computer of a 2001 engine. I would have to put the "turbine" versions of the flow meters on there and so far, I have been unwilling to cut the hose to put them in there. Wish I could see the top of the tank like your pictures, I'd replace the sending units, have not tried too hard though.

The fuel will even remove botom paint on the lift when it "sloshes".

Charlie

kmcclish · Posted: Tue Jun 01, 2010 10:22 pm Post subject:

Hi Bryan,

I had the same problem on my 2008 Venture 23'. I installed a couple of "vent whistles" on the fuel vent line that I bought from greenboatstuff.com. They cost about $25.00 each, but stopped the spill problems that I'd been having. You have to make sure to stop filling when the whistling stops! People who observe your boat in gas stations while filling seem to be somewhat alarmed about the very loud whistle when filling your tanks. When that whistle stops, the tanks are full! Don't keep filling or for sure you will spill or the fuel will leak on a warm/hot day.

Solved my problem. Good Luck!

Kent
MARCIA JANE

rogerbum · Posted: Tue Jun 01, 2010 10:37 pm Post subject:

Also, if you are filling on the water, you should have a bottle over the vents to collect any excess that may escape from the vents. I don't know who makes them but there are bottles that can be placed over the vent and which have suction cups to hold them to the side of the boat. That prevents spillage into the water.

Beflyguy · Posted: Tue Jun 01, 2010 10:56 pm Post subject:

The whistles sound like a good idea although I had already parked the boat in the driveway for a couple of days then used it for a couple of hours, then parked it back on the driveway overnight before the problem occurred. I would have thought the fuel level would have been a few gallons down by that time or that the problem would have showed up when it was full in the driveway.

Wefings · Posted: Tue Jun 01, 2010 10:59 pm Post subject:

Davis Instruments makes the bottles . They were way ahead of their time....
Marc

thataway · Posted: Tue Jun 01, 2010 11:02 pm Post subject:

Yep--it is a problem--worse on my starboard side. It is well documented in the past. But search engine is difficult to find this type of issue.

The problem for me is that it has damaged the vinly decal for the boat name and prot, plus stains the dark green Gel coat. Mine is a bit compunded by being in a lift, with the stern down by several degrees.

Our senders at not at the back of the tanks like this.

My suspician is that the tube which is welded onto the top of the tank goes too far into the tank--is too long. I discussed this with the Reynolds, they said "take it up with the tank builder" who never responded.

The "solution" is to put less fuel in the boat, especially if you are going to store it. You could take the tank apart--but that means taking the boat apart--you have to live with it unfortunately.

We have "cut the lines" on 4 boats--no big deal--and definately worth doing. The nly problem is that occasionally the turbo flow meters go out and have to be replaced.

Beflyguy · Posted: Wed Jun 02, 2010 1:04 am Post subject:

I think I might have to add a connection from the filler hose to the vent. Does anyone know the diameter of the filler hose?

Mike... · Posted: Wed Jun 02, 2010 2:27 am Post subject:

matt_unique · Posted: Wed Jun 02, 2010 7:44 am Post subject: Fuel

Hmmm...I only ever noticed the fuel squirting from the vent when filling to the brim (meaning well past "F" on the fuel gauges). I think it's prudent to leave a little bit of room for level changes when getting on plane and such.

Of course fuel will expand when warmed - I don't think you have a specific problem if you filled her to the brim then was exposed to heat in your driveway. With a 330 mile range - we usually don't need to top it off and carry the unnecessary weight. I fill as much as I need plus a 1/3 more for contingency.

Charlie - your sending units are not as hard to get to as you think. Remove your line storage boxes (about 8 screws each side) and you will have all kinds of ambient light and space to work.

Captains Cat · Posted: Wed Jun 02, 2010 10:19 am Post subject:

Thanks Matt, I'll try that. I really need gages that work!

matt_unique · Posted: Wed Jun 02, 2010 10:25 am Post subject: Yes

Alok · Posted: Wed Jun 02, 2010 12:35 pm Post subject:

The "vent overflow" bottles do not work on the Tomcat...at least the ones sold by WM.

The rub-rail placement prevents the bottle mouth from getting a tight seal around the vent. I just hold a large piece of fuel-absorbent cloth under the vent when refueling- sometimes the vent will burp fuel way before the tank is anywhere near full.

Beflyguy · Posted: Wed Jun 02, 2010 2:41 pm Post subject:

I think I figured out what is happening. The tanks are about 90% full and I backed down a fairly steep hill to park the boat in the driveway where the stern is a little lower than the bow. There is probably an air bubble at the front of both tanks that is expanding with the warmer temperature and the air cannot get to the vent so it is pushing fuel out.
There should probably be a vent at the front of the tank also but I imagine there is only one at the rear.