Having problems with your 2000 GMC New Sierra 1500 ?
Gas gage allways says full 1999 gmc serria - 2000 GMC New Sierra 1500
Check ground on tank gage
UUUgh....you may have a bad sending unit inside the gas tank. They are seemingly a high maintenance item after a few years with many vehicles. If you are lucky your car has an access area above or behind the rear seat that will allow you to take the unit out of the gas tank. If you do not have this access and I suspect you do not, then you will need to drop the gasoline tank out of the car to get to the darn thing. The fuel pump is usually on the same stem that you will remove from the tank with gauge variable resistor unit. Due to the trouble of removing the tank I would recommend replacing the fuel pump inside the tank at the same time just because...just because...sometime you will have it go bad also...might as well change it now along with the gauge sensor.......but.....before you go to all of this trouble have someone put the car on a lift and examine if you can the wire that goes to the top of the gas tank that goes to the sensor inside the tank. If the wire has come loose and touching body metal somewhere then your gauge may show full all of the time...if so...simply reconnect the wire to the terminal on top of the tank and you are back in business without having to go to all the trouble mentioned above. On extremely rusty cars underneath I have had to run a completely new wire from the gas tank snaking it up under the dash board and connecting it to the gas gauge to fix the problem. The sending unit inside the tank is really suspect though as they do bad. They are very crudely made by winding a coil of bare wire on a insulated cone and having a poorly made spring loaded wiper blade connected to a float causing the wiper blade to rub up and down along the cone shaped coil of wire so that this all forms a variable resistor that changes the current going to the gas gauge. You will notice that the gauge is not linear...that is when the gauge gets close to empty you may still have plenty of gas actually in the tank and also the full tank level may fall rapidly at first etc. This is due to the cone shaped coil. They could have put it on a cylinder to make it a linear gauge but did not want it to be that way. If you do have to remove the gas tank and replace the gauge sensor(and by my recommendaton the fuel pump as well) you will find on top of the tank a sealed unit maybe 4 inches in diameter that is held in place by a sealing ring that pushes on a rubber "O" ring. Take a hammer and large flat screw driver and hammer on the tabs of the ring to rotate it in the direction to free it up for removal of the units inside the tank. Assembly is the reverse....but make sure you get a good seal with the large rubber "O" ring so that you do not have any loss of gasoline going down the road.
Repair Help & Product Troubleshooting for 2000 GMC New Sierra 1500
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