A connector that has higher than normal resistance but is otherwise OK can cause the guage to read lower than normal at all times. That is if it is the same as GM (and most brands are). Take the gauge wires at the tank and disconnect them (if you can, I've never looked at it) then cross them. Make sure your crossing the correct wires first. The gauge should peg full. This will tell you nothing, but you'll know the gauge is capable of reading full if all else fails.

If someone out there knows I am wrong about this, speak up. This works on 90% of cars I've seen so I'm just assuming it'll work on a Mitsu.

Clay