87 K-5 Blazer fuel gauge problem

I have a 1987 K-5 Blazer,350 throttle body carb. I bought it from somebody after it sat for a year and a half:frown:. It smoked a little because of the rings set up. But that problem has gone away now after some good running:) My question is that the fuel gauge is pegged all the way over to the right. I topped off the tank a few times thought that would help but nothing,still stays far right. I notice sometimes when key is off, then turn key to right before I would start it, gauge does move a fraction but to the right and stays there. Is this a bad ground some where? Or is sending unit shot? Thanks for any answers. For a 1987, body is sound on this Blazer with very little rust on the out side and under the vehicle. Thanks for any reply!

If the fuel gauge indicates full when the ignition is in the RUN position, there is an open circuit in the fuel level indicating circuit.

If the fuel gauge indicates empty when the ignition is in the RUN position, there is a short to ground in the fuel level indicating circuit.

Thanks Old master for the quick reply!! what should I do next to fix this open circuit thing? Gauge needle just stays to the right. Do you think it's in the sending unit in the tank or is it something maybe I can get at from the outside? Problem in a wire? Thanks again!!

Make sure all fuses are good, check both sides with a test light or volt meter.
The black with white stripe wire at the fuel level sender connector must show less than 5 ohms resistance to ground.
The purple wire at the fuel level sender connector should show a pulse voltage with the ignition in the RUN position.
The two terminals in the fuel level sender should not show an open circuit. (resistance will vary depending on fuel level.)

Thanks again old master for all the help and guideing me in the right direction!! :)

No problem, please post your results, or any more questions.

Old master, Today I looked under vehicle, ground wire seems to be ok little rust where it's attached to frame but I can clean and put a new end on wire if need to. The other wire that goes to sending unit seems to have a little green corrosion on end where it goes into that little round plastic piece. Is that a spade type connection to that plastic piece. Don't want to pull on it and break something before I know how it is attached, Thanks!

Rust and corrosion, (that green fuzz), are exactly what you're looking for! They cause high resistance, which causes the gauge to read high. The connector that plugs into the sending unit most likely has round pin type connectors. There is also some type of latch on the connector that will need to be released before unplugging the connector. After you see what's going on, you can determine what needs to be done to correct it. You're on the right track!