Just a warning that may help others if you ever had fuel supply issues with a Mercury or Mariner with the 25l tank like the one in the link below.
As I couldn't find the exact one I've also attached a link of a near identical Yamaha pickup pipe which shows the type of spigot assy-pipe-filter pickup arrangement under the fuel gauge/connector.
When servicing my outboard today I undid the 4 screws and pulled out the fuel gauge/pickup pipe assembly. This had the same issue as the last tank I had of this type.
The pickup pipe is quite a loose fit on the spigot it connects to under the gauge/connector unit and relies on a bead of brittle glue at the top to seal. It is slightly over length so the plastic filter "foot" sits on the bottom of the tank (with four little stubs so it doesn't block/seal on the tank bottom) and I guess the fact it touches the bottom should stop it falling off.
The issues I've found on both tanks are that the glue bead has broken where it joins the top spigot and it might be possible to pull some air in.... and also due to the pipe being a little over-length it has kinked halfway up reducing the fuel flow area to about half with the possibility of fuel starvation if it got worse.
I've sorted the spigot fit by slightly tightening the pipe with a cable tie so it is a good interference gripping fit plus adding a bead of fuel resistant silicone. Where it's kinked I've again used a cable tie to pull the shape back to round.