fuel gauge showing empty when full sometimes

Jeff1 · March 12, 2005

I have a 99 seirra and sometimes the fuel gauge will show empty with a full tank. It changes between full and empty periodically. Also I have some hesistation at times, especially after it if first started. I have changed the fuel filter a few times to no avail. I have also added injector cleaner to my gas a few times with no results either. Could this be a problem with the fuel pump, or gas cap maybe? I'm confused. Thanks.

budhayes3 · March 12, 2005

As far as the fuel guage goes, the sending unit in the tank is a common culprit. For your hesitation, I'd start by making sure that your tune up parts are all good (spark plugs, wires, air filter, pcv...you mentioned that you already replaced the fuel filter). It's also a good idea to clean the throttle body and do a top end clean periodically. Do a search on "Seafoam", and you'll find a ton of info about the top end service. (Cleans out the intake, valves, and combustion chambers) One last thing, just for poops and giggles, pull the vacuum line off of the fuel pressure regulator and check for the presence of fuel, if there's gas in there, it's leaking and should be replaced. (fp reg is located on the driver's side fuel rail)

guiness · March 13, 2005

I have a 2000 sierra ext cab 4wd similar problem. About 2 years ago it cranked for 10 seconds before starting. GME wanted $1000 for both regulator and fump. Changed the fuel regulator under the hood in about 2 minutes and that solved the problem ($45 for the regulator). However. last weekend after filling the tank, the low fuel light came on and fuel gauge would not come off full. Bought the combination electric fuel pump and sender unit from carquest for $330 and installed it myself yesterday afternoon. I did it on the ground, but I believe I would remove the bed if I did it again. The pump is on top the tank directly under the floor of the bed. I understand there are 6 bolts and a wiring harness to remove and a couple guys can remove the bed. Runs great. Don't forget to attach the ground wire to the frame for it to work. Basic tools are all you need and you reuse the plastic hose retainers off your old fuel pump. Don't be in a hurry and it is well worth doing it yourself if you are thinking of it.

Jeff1 · March 13, 2005

Thanks guys. I should have mentioned I only have 64k on the truck, and I have the K&N FIPK, Hypertech PP and 160 stat. The air filter is clean, but the plugs are factory. I will look into the things mentioned for a possible fix. I have always heard it is easier to remove the bed to replace a fuel pump, but a friend of mine swears it is easiest to drop the tank to the ground. I have no experience with either.