This will take a while but please read.

I have a 1988 300ZX 2+2 (ANALOG COMPONENTS). When I purchased it the gas gauge never worked. I changed the sending unit 4 times thereafter finding out the analog and digital are different. So I bought a fifth one with no luck. In between all these sending units a destruction of wrecked Z's I took the initiative to test the gauge its self. It moves forward and back again with a simple power pack and the switching of current from one side to the other. Now I have tested this thing 1 billion times and I know it works. Then I decided that with a lot of power of course it will move lets try with one AA battery. It moves. I left the plugs in the back of the instrument cluster and follewd where they went to the circut board and tested in my own way and I have 100% awknowledgment that I did it correctly and then ran wires to the back and tested. I did it all OK. I changed diodes in the back of the circut board thinking they were bad but no change.


I have power from the front to the back because when I take the sending unit out of the tank and move the float all the way to the full position the needle goes up but if I move it slightly down the needle goes to empty. Even with the float in any other position other than all the way to the top the needle stays at or goes to empty. I know all my wires go from the dash to the back and all the ground are good. I mean I am just stumped. Anyone have a gas gauge problem like this and fix it. I need major insight on this.

try using the new model from courtesyparts.com... it's a better design and doesn't rely on pads that can become tarnished easily from the gas...

http://www.courtesyparts.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=CP&Product_Code=25060-Z31AN

if you're pulling units from junked z's there's a large possiblility that they don't work either... if i just skimmed over your post and missed that you tried cleaning and testing them before installation my apologies, but you'll find the procedure to do so about halfway down the page on the following link

http://www.zeeyalater.net/comprob1.htm

hope that helps

if I missed about the cleaning part yes I did clean the stick on the inside of the aluminum tube with a very very fine steelwool and all the black tarnished crap off.

yeah, i tried cleaning mine on the 88 and it didn't help it at all... so i'm going to try replacing it with a new unit one of these days once i'm back with the car... i know the gauge works properly because it does go up to 1/3 tank and drop off quickly from a full tank...

The Only thing I havent done is try a different gauge. I tryed to get the one I have out but I think Ill break something. Anyone have info on how to get it out with out having to replace my whole cluster. I have a very nice WHITE read out cluster BTW instead of the UGLY Orange.

i think the 87+'s have the nice white face gauges, but still the lame orange rear lights... anyway short of removing the flexible circuit board on the back and tearing it open and apart to even see if you can, i'm not sure if there's anything else you can do... aside from make yourself a new fuel cell with a different fuel gauge in it lol... :banghead: