I dropped the fuel tank this past weekend to replace the fuel pump and the fuel pump strainer. I noticed that the ground wire on top of the sending unit was almost broken off so I re-soldered it back to the tap. I put everything back together and tested to see that the pump was running before lifting the tank. The Blazer starts fine now but the fuel gauge sits well past the full mark all of the time ... Key On or Key Off ... The oil pressure gauge sits at zero till you start the engine. Then it goes to max. What could cause these two gauges to stop working? I was careful not to damage the float arm and it moved freely.

 

did it just start doing this? becasue the solder could have short circuted a wire when you soldered the ground

 

Yes it did just start after the install. The solder was only on the ground tap connector that is on top of the sending unit. Not the wires that provide power inside the unit. The tap connector is actually factory welded to the top metal piece of the sending unit.

I read somewhere that this could indicate an open circuit ...

 

from my experience everytime the gauge reads way past full it means there is no ground. maybe where the wire is attached to the frame is rusty. i had a burb where i soldered the wire to the sending unit and it didnt work. i ended up jamming a sheet metal screw into it and that made it ground out.

 

Thanks abig84. I will start with the ground this morning.

 

Ok ... Checked the ground and it seems to have a good ground. One thing that i noticed today is that when I disconnect the connector for the sending unit the gas hand goes even further past full. When I connect it the hand moves back to past full. Hoping that I do not have to drop the tank again to replace the sending unit.

Any suggestions anyone?

 

well maybe you could have a open wire and it is short circutting