Bimini 306 Fuel tanks and fills

[Mikesbimini]

Hello everyone I have searched this question and have not found the answer. I have a 1998 Bimini 306 and it has 2 fuel tanks. One tank is 150 gallons and one is 156 gallons. I believe one is forward and one is aft. I also have the two fuel fills on the starboard side. Can somebody tell me which fuel fill goes to which tank as well as which tank is the main and which tank is the auxiliary. My owners manual does not show a fuel system diagram. If anyone has one please post it.

Thank you,

 

[seasick]

Usually the larger capacity is the main. If you pull the deck inspection plates over the tank senders, you may be able to see a spec decal on the tank. It may be covered in dirt. If you don't see the capacity decals, pull the deck plate over the fill and vent tank connections. The forward most fill is for the forward most tank but whether that is called main or not I am not sure.
Another way to tell is to look at the tank selector valves and follow the plumbing. That may be tough to do.
There are many ways to determine which tank is main if that is what the valves and tank gauge selector say. Pull off the pink wire on the sender on a tank and see if the gas gauge drops to empty. If not, flip the tank switch (not the valve). The display should read empty.

 

[Mikesbimini]

Usually the larger capacity is the main. If you pull the deck inspection plates over the tank senders, you may be able to see a spec decal on the tank. It may be covered in dirt. If you don't see the capacity decals, pull the deck plate over the fill and vent tank connections. The forward most fill is for the forward most tank but whether that is called main or not I am not sure.
Another way to tell is to look at the tank selector valves and follow the plumbing. That may be tough to do.
There are many ways to determine which tank is main if that is what the valves and tank gauge selector say. Pull off the pink wire on the sender on a tank and see if the gas gauge drops to empty. If not, flip the tank switch (not the valve). The display should read empty.

Do you have a Bimini 306? Some of the things you are telling me to check are either not on my boat or I don’t understand your nomenclature. For instance my boat doesn’t have vent tank connections and there is no deck plate for my fills. My fills are on the starboard gunnel.

 

[Mikesbimini]

Can anyone post a fuel system diagram of a Bimini 306 or a 300 Marlin which I think is the same?

Thanks

 

[seasick]

Your tanks have vents but probably integrated into the fill fixture (what we call a combo fill, the thing you put the gas nozzle into).
Yes the fill fixtures are usually on the gunnel but that is not what I was talking about.
On the deck of your boat (floor) there will be various round pop out access plates. There will be one over the area of the tank where the sender connections are made. There most likely is also one over the section of the gas tank where the fill and vent hoses connect to the tank ( in your case there will be access over both tanks).
There is a switch on the dash that selects one of the two tanks. With the ignition on, see if the gas gauge reads something other than empty or full and then switch the switch to the other position to see if the display changes. This is a test to see if both tank fuel level senders are working.
The owners manual mentions the deck plate but doesn't show the position of the gas tanks. It shows the fuel tank selector valve as having the tanks marked ae Main and Aux as does the guage selector switch.
Here is a link to the owners manual

https://gradywhite.blob.core.windows.net/media/22220/1998-306.pdf

 

[Mikesbimini]

Thanks for your response I have identified the two access plates. One is on the deck between the bench and helm and it has two access covers one shows the sender the other shows the fill hose and vent and looks like the lines leading to the tank selector valves. The other access for the second tank is aft of the first behind the bench seat and it only has one deck plate for access to the sender. My senders are the digital NEMA senders and are connected to my NEMA network. I don’t think the switch on the panel is connected to a gauge since I have the electronic Suzuki C10 gauge reporting fuel levels from those digital fuel senders. I’m wondering if the forward tank is filled by the forward fill and if the aft tank is filled by the aft fill. Just as important I’d like to know which tank is the main and aux so that I know which one I’m using when I select it with the selector valve.

Thanks

 

[SkunkBoat]

fwd fill goes to fwd tank..always..unless someone crossed the hoses since the boat was built

The larger tank is usually designated as MAIN....unless someone crossed the hoses to the valves since the boat was built

One tank has a pink sender wire which should be Main or "Tank 1" on your NMEA setup. The 1998 306 manual shows it on the fwd tank
The other tank has pink w/ white stripe which should be Aux or "Tank 2" on your NMEA setup.
...unless someone crossed the sender wires since the boat was built

as Seasick said you can test it very easily and you can read the tank labels to see which is the larger tank (Thats a good thing to know)

 

[Fishtales]

156 is main and it is closest to helm. 150 aux and aft. Same with the fills, fore is main, aft is aux.

 

[Mikesbimini]

Thanks everyone I appreciate all of your responses. I will look at the manual again to see where it mentions pink sender wire as main. Interesting I will look thru the manual again. If I had seen that in the manual I wouldn’t have wasted anyone’s time in here asking. In any case I hope this helps someone else as much as it has helped me.

Thanks,