Fuel fill restriction

[Inky]

I have 2008 30’ Bimini. I am unable to fix the main tank. It take an hour to put 100 gallons of gas in the tank. The auxiliary tank fills normally. Anyone have this problem? Any suggestions? Thanks

 

[VeroWing]

Slow filling sometimes indicates vent line clog. Check to be certain vent is clear of spider/bee nests.

 

[Halfhitch]

Inky, With that level of restriction I would expect to find the fill hose, usually 1 1/2 inch, has a droop in it causing the hose to have a section in the low portion of the droop that is totally full of fuel which is preventing any breathing of pressure from the tank. Then I would be expecting to find that the vent hose either has a kink in it, a droop in it causing a puddle of fuel that prevents breathing of tank pressure, or an insect caused blockage if there is a through hull vent. Be advised that the riggers of most production boats cut the hoses for the boat they are working on plenty long to make sure they have enough. They are always pressed for time and often do not take the time to check for the proper slope of the hoses to prevent sagging or kinks when the extra length is shoved into a void so the end of the hose can be pushed onto the nipple. When we as owners do this job we make sure all is perfect before we close it up and if it isn't we recut the hose till it is. Many times that step is not taken. If your vent is blocked the air in the tank that is being displaced by the fueling process has to pass back up the main fill tube. If that tube has a droop filled with fuel, pressure will build till it lifts that puddle and burps that fuel out of the way. If you try to fill really fast it may burp fuel completely out of the boat. If you trickle it in the burp will be smaller and just cause a gurgle down in the hose.

If it were my boat I would be looking for those conditions as a starter. Remember that both the filler hose and the vent must have a continual down grade to work properly.

 

[seasick]

In addition to a blocked/bad vent(either separate or part of a combo fill) You could have a low loop in the vent hose. If this problem is newish and you haven't replace fill and/or vent hoses, a low loop is unlikely
You could have blocked fuel line itself. A somewhat common problem is some foreign object obstructing the fill hose. The cap liners from additive bottle are a common culprit.
First determine if you have a combo fill.vent fitting. If not, check the separate vent thru hull. As mentioned. bugs, nests and crud buildup are common.
If the problem with filling gas happens as frequently with an empty tank and a mostly full tank, a blocked fuel line is more likely. If the problem seems to happen less when the tank is emptier, you are more likely to have a blocked vent. ( more air space in the tank so it takes longer to build up enough back pressure to trigger the nozzle shut off feature)

Try running a small snake down the fill hose to see if you can clear any obstruction. Make sure the wire or snake you use has a plain end, not hooked. A hooked snake can get caught in the fill and will be very difficult to remove..( To be honest, this suggestion has not been super productive in my experience)

 

[Halfhitch]

If you do as seasick suggests and try a snake down the fill hose, make sure you don't use a steel plumbers snake. The hose has steel wire reinforcement that could be exposed and what ever has been lost down there could be steel. Steel on steel can possibly make a spark. Something non conductive ideally for your probing. There are exploratory cameras that are sealed against explosive atmospheres but removing the hose is cheaper.