when full it reads between 1/4 and 1/2 but then gets accurate once fuel level drops to that level and below? Also if I turn the lights on it goes down about 1/8 of a tank?
Any ideas?

Bad ground somewhere?

Skip

There might be more than one issue here. But, you may want to check the sending unit that resides in the tank. Sometimes a little corrosion will keep the float from moving up and down freely. My guage stopped at 1/4 mark. I didn't know this until one day I ran out of gas with it still reading 1/4 left. I took out the sending unit (carefully) and there was just a little crud on it. Cleaned it up, put it back in and no more problems. Try this.

I just had this issue with the 75 I just sold. Removed the sender, took it all apart, (on small 4mm?? nut at bottom of sender, and the rest is press fit, slower pry it open with small screwdriver) the pole that the float rides on was all flash rusted, little WD40 and 1000grit and I had the float moving free again. Put everything back the way it was, and no further issues. If you plan on tackling the project (it's not hard) two things to be aware of. 1. Unhook the battery before you start 2. Take care and don't drop a bolt in the tank when removing the expansion chamber or the sender itself.

Ferg

Be very careful if you sevice it, the thin guide wires on the sending unit are very easily broken.

On the plus side new senders are only ~100 dollars if you do break it.

I think it is pretty common thing that the sender float sticks especially if you have a rusty tank.

that, and i'd check all the grounds just to be sure. the gauge itself rarely breaks ...
Andy

how do I get at the sending unit? That was my first thought, Do I remove plastic catch tank and then ? thanks, Matt

Sending Unit is on top of the tank. Unscrew and pull out.

Do a search on this topic... there was a VERY good write up on how to recondition a sending unit.

The search feature is your friend.

Quick check for float is to tip it over. You should hear it go from the top to bottom. If stuck, shake vigorously. I have freed up several this way. No disassembly required.

A little help:
http://www.icbm.org/cmgallery/thumbnails.php?album=58

when you have the sender out and the tank is VERY low (i would empty it first) on fuel, now would be the time to examine the area in the bottom of the tank where the outlet and fuel return tubes are. you should be able to see the sock/strainer too. if the bottom of the tank is a mess be prepared to pull it. the whole process is much eaiser with the tank out to begin with.

k