Replace Fuel Sending Unit

[MPKehoe09]

I have been using a topside fuel tank on my 1998 175 Osprey due to the previous owner's retrofits to the fuel tank.
I wasn't quiet sure how to address this issue, and have been putting it off for the last year.

My goal is to replace all the fuel lines, and install a new sending unit.

It seems that for some reason, the last owner epoxied/plastic welded a cap where the fuel sender use to be.

Do I try to remove this cap, and install a new sending unit in the same location?
Or do I leave the cap "as-is", and find a new spot for the sending unit?

Either way, it looks like it would involve cutting into the tank...
I have basic tools (drill, dremel, etc.) but am concerned about gas vapors and any sparks from the electric motors.
The tank could be empty, or it could be some very old fuel from the prior owner(s).
How would you recommend doing this?

Lastly, if I were to cut that old cap out, I will have a larger opening than I would need for the sending unit.
Would I mount the sending unit to a piece of Starboard or similar material, and fasten/epoxy the starboard to the tank?
I'd obviously account for the thickness of the starboard when purchasing the new sending unit.

Or, perhaps there is another option that I haven't thought of.

Curious to hear what you would do if you came across this.

Thanks in advance,
Mike

[mshugg]

Epoxy will not bond well to starboard or your Poly tank.  You really need to create some kind of mecahical connection to make a lasting repair.  You could possible make two aluminum plates oversize for the hole in the tank.  The plates sandwich your tank.    You could thread the lower plate for machine screws and use a gasket compound to seal everything up.  Your new sending unit would mount to the plate.

Warning:  in no case should you use a power tool or otherwise cut the tank until you are 100% sure that there is no fuel or vapors.  Empty the tank of fuel and fill with water to void vapors.

Honestly, I'm not a fan of messing with fuel.  You'd be safer and ahead on time just replacing the tank.

[Motox125]

I bought this boat and am in the process of repairing the tank / sending unit.
I'm finding this post and wish I had known the right questions to ask or where to look when I bought it but this is my first boat... live and learn I guess..
The cap shown in the pix was not sealing and this is a low spot so years worth of water entered the tank.  About 2 gallons.
All of the inserts were rotted away and the epoxy made a mess of the surface.
In the process of trying to clean things up I tried to move fuel pickup out of the way and it snapped off.
If anyone has questions I can provide pix and details of the fix I'm in the process of attempting.

[boatnamesue]

I bought this boat and am in the process of repairing the tank / sending unit.
I'm finding this post and wish I had known the right questions to ask or where to look when I bought it but this is my first boat... live and learn I guess..
The cap shown in the pix was not sealing and this is a low spot so years worth of water entered the tank.  About 2 gallons.
All of the inserts were rotted away and the epoxy made a mess of the surface.
In the process of trying to clean things up I tried to move fuel pickup out of the way and it snapped off.
If anyone has questions I can provide pix and details of the fix I'm in the process of attempting.

I recommend starting a new thread since this one is almost a year old.