Can't (Completely) Fill Boat's Gas Tank

[SouthernWake]

How do you define “appears to be full”?

How large is your tank and how many gallons can you get in?

[Black Bart]

The fuel will "bubble" up to the top to the point
I can't add any additional fuel.

30-gallon tank; never been able to get more than five gallons or so in the tank.

[Black Bart]

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They claim that the little hole next to the chain is the vent. Is that even possible?

[JABIII]

The fuel will "bubble" up to the top to the point
I can't add any additional fuel.

30-gallon tank; never been able to get more than five gallons or so in the tank.

I am sure that you have tried it, but I can load 64 gallons and then have to feather the last 6 gallons in which takes about a third as long as the first 64...

[mello_collins]

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They claim that the little hole next to the chain is the vent. Is that even possible?

EPA crap not wanting vented tanks. Run a separate vent.

[SouthernWake]

Even with a bad vent you should be able to feather it to the top.

Analog sender?
What if there is no tank problem and you just aren’t burning that much gas on a trip?

[Black Bart]

Gonna take it somewhere else. Surprising how difficult this seems to be. Particularly for "professionals" who do this stuff for living.

[mello_collins]

You have scducks. Who needs anything else.

[wskinner]

You have scducks. Who needs anything else.

I think he meant Facebook.

[DG34YF]

Possibly the long horizontal run forward:
1) hose or tank shifted or something else fell on top of hose causing crimp
2) additive put in after fueling, sat in line & caused hose to deteriorate/swell
3) fuel added at one time had more ethanol than quality of hose rating
4) poor quality hose to begin with

Newer builds have mechanisms @ tank protrusions that can hinder filling

Moving fill location will assist filling if it results in shorter distance to tank fill opening & no crazy turns.

New stuff: Dawn used to take care of all the crap they have come out with!
https://www.criboats.com/knowledge-b...l-the-way-why/

[BigBrother]

First thing I'd do is replace all hoses. Fill and vent. Do you have a secondary vent? Those internal vents are crap. Also I was having the same issue until I changed my bunks. Bow was lower than the transom on the trailer and my tank fill and vent were located in the front of the tank (bow).

Also...look at your fill line. does it go below the deck and then come up to the tank? That belly below the fill port could be what's giving you fits.

[centurian]

First thing I would do is drain all the fuel from the tank to see how much fuel is actually in the tank, if not a clear plastic fuel tank. Also a good time to check your fuel gauge operation. Then see how fast and to what extent it refills

[BigBrother]

First thing I would do is drain all the fuel from the tank to see how much fuel is actually in the tank, if not a clear plastic fuel tank. Also a good time to check your fuel gauge operation. Then see how fast and to what extent it refills

agree. only filling 6 gallons in a 30 gallon tank sounds weird. If you decide to pull the sending unit, be sure to note the direction the wire comes out and duplicate it. those screw holes arent perfectly aligned. They are offset and you'll drive yourself crazy trying to get it lined back up like it was the first time. Learned this lesson the hard way.

[centurian]

Also make sure when sitting on the trailer the vent connection on the tank is not lower than the fill connection. I had gas leaking out the vent line on my boat in the shop i lowered the tongue jack and it stopped dripping so just sitting there jacked up put the vent connection under the fuel level. Not a problem in the water or hooked to the truck.

[Black Bart]

Thank y'all for all of your help. As many of you suspected, it was indeed venting issue. Marshall Marine either 1) lacks techs who are capable of assessing, much less fixing simple fixes, and/or 2) never took the time to do anything because it wasn't worth their time. Either way, it's a bad look for them.

Neighbor and I removed the existing intake and replaced it, as well as adding an actual stand-alone vent. Boat then took as much gas as I cared to add. Problem solved.

I know this is child's play for many of you, but I'm late to the party and catching up as fast as I can. Your help is one of the reasons I love this site. Thanks again, sincerely.

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[mello_collins]

Just be aware that dirt dobbers love vent holes. If it all the sudden stops working that is probably your problem.

[ecu1984]

Glad you got it fixed.
Be aware that a vent is sucking in air to replace the gas that is being pull out to the motor. It actually has suction on it when running.
If any spray or rain is hitting that stand alone vent while running, it will be sucked right into your tank (water in gas).
The holes in that stand alone vent need to be pointed toward the rear of the boat and/or put a $10 "clamshell" over it