Last night I saw that a "Petro" station in the hood had 87 for $3.03 a gallon. That's almost 20 cents cheaper than most places around here, so I decided to fill up. Gauge was showing between 1/2 and 3/4 full. I added a little over 7 gallons, which is about right for where the gauge was at. I let the pump click off, I wasn't trying to round up or anything like that.
On startup, the fuel gauge went way past full. Normally it goes just a hair over the F mark when full, but this was more like a solid 1/8" past the F...noticeably higher than it has ever read. I had time to burn and apparently a very full tank of gas, so I drove around to see if it would move at all. No movement after 20 miles. I got home and shut the truck off, then turned the key to the on position. The gauge then dropped down to where it should be. I hoped that would be the end of it, but not quite.
Today I started the truck up, the gauge read fine, and I drove a couple miles to a store. Come back out and start the truck up...CEL immediately catches my eye, and of course the fuel gauge is pegged way past full again. The code was P0460, "fuel level sensor circuit malfunction" (oh really?).
So I drive home, shut the truck off, then turn it on again. Fuel gauge drops back to normal, so I cleared the CEL. I've driven it about four times since then and the CEL has not returned, fuel gauge has behaved normally, and it seems to be at the correct level (I reset the trip odo every fill up).
Any ideas why my fuel gauge went nuts after this fill up, and has anyone experienced fuel gauge behavior like this? Does it sometimes take a sending unit a while to die completely? Is it possible the float got stuck or hung up somehow and is now free again? The fuel pump/sending unit are completely original and have never been out of the tank, wiring has never been messed with or disconnected. I am hoping this is just a fluke and not a sign of impending sending unit failure.
I plan on putting some Techron in the tank just in case it's related to varnish or something "gumming" up the sending unit. My truck has had a lot of off brand fuel of unknown quality run through it over the past month and a half, so I guess anything is possible.
On startup, the fuel gauge went way past full. Normally it goes just a hair over the F mark when full, but this was more like a solid 1/8" past the F...noticeably higher than it has ever read. I had time to burn and apparently a very full tank of gas, so I drove around to see if it would move at all. No movement after 20 miles. I got home and shut the truck off, then turned the key to the on position. The gauge then dropped down to where it should be. I hoped that would be the end of it, but not quite.
Today I started the truck up, the gauge read fine, and I drove a couple miles to a store. Come back out and start the truck up...CEL immediately catches my eye, and of course the fuel gauge is pegged way past full again. The code was P0460, "fuel level sensor circuit malfunction" (oh really?).
So I drive home, shut the truck off, then turn it on again. Fuel gauge drops back to normal, so I cleared the CEL. I've driven it about four times since then and the CEL has not returned, fuel gauge has behaved normally, and it seems to be at the correct level (I reset the trip odo every fill up).
Any ideas why my fuel gauge went nuts after this fill up, and has anyone experienced fuel gauge behavior like this? Does it sometimes take a sending unit a while to die completely? Is it possible the float got stuck or hung up somehow and is now free again? The fuel pump/sending unit are completely original and have never been out of the tank, wiring has never been messed with or disconnected. I am hoping this is just a fluke and not a sign of impending sending unit failure.
I plan on putting some Techron in the tank just in case it's related to varnish or something "gumming" up the sending unit. My truck has had a lot of off brand fuel of unknown quality run through it over the past month and a half, so I guess anything is possible.