gas guage question

my gas gauge does not read unless i am running out of gas. when i am running low on gas the needle moves UP to E. I dont know wheather it is the gauge or the sending unit? any input would be great.

One of my mazda's was doing the same thing, I was going to replace the sending unit but it was actually the plug that connects to the sending unit was corroded, I cleaned it up and worked fine. You might want to give it a try first.

The stock Mazda sending unit is a poorly designed POS. And post on here have had a problem with them at one time or another. If dragginmazda86's commnets don't help, you will probably have to drop the tank, pull out the sending unit/fuel pickup and either attempt to clean it up or just replace it. Do a search for similar issues on the site - there should be plenty of info.

thanks for the help. I will try it after work today. i will let you know the results

Get out your multimeter (if you don't have one, RUN to Sears this morning and buy a digital one on sale half-price for $10, worth its weight in gold, I have three at various places). Set up in the resistance or ohms scale, touch the leads together, and record any ohms resistance (subtract this amount from subsequent measurements). Sending unit out of truck; hook up the multimeter leads and physically move the float up and down, measuring the ohms resistance at various positions. Here's the factory ohms resistance at those positions:
Empty: 103-117 ohms
Middle: 28.5-36.5 ohms
Full: 1-5 ohms

Apparently there are different sending units for the standard, long bed, and cab plus versions as the manual lists different distances for the arm to be in for those three positions for exact measurements. There should not be areas of zero resistance in between either, should be relatively linear with regards to float position on a good unit. To fully check out the gauge, one must apply 7 ohms for full, 32,5 ohms for mid-way, and 95 ohms for empty, but that requires a different, more expensive tool.