I have seen post about erratic fuel gauges but I'm having another issue I can't seem to find anything on. It seems my fuel gauge is going from full to empty to quickly (not erratically). I had just bought my 2002 4dr blazer with 95,xxx miles and just filled it up for the first time. When I filled it the gauge was low and the low fuel light was on, it only took about 11 gals, but I have just put 20 miles on it and it's already at the 3/4 mark on the gauge. Any suggestion would be greatly appreciated. Thanks

 

Did a few calculations and if they're correct, you're either getting really bad fuel economy (roughly 12 mpg) and the range of the fuel gauge represents half the tank, or the sending unit is just bad and doesn't represent the amount of fuel at all. The 20 miles you drove, was it in 4wd? Were you burning fuel quickly? like accelerating quickly, etc.

 

Thanks for the response. Since I last posted, I'm at about 50-60 miles with the gauge saying just above the half mark. My driving up to this point have been slow and steady, so no hammering on the gas. It did throw a service engine light though, code was P0101 (MAF I believe) so maybe it could be running rich but that's pretty excessive to already be at the half empty mark for only 60 miles. I will be stopping at the Gas station tomorrow though and filling up again so I will get the correct MPG. But I think I'm leaning towards the sending unit as well, my guess it's the original one.

 

Just fill it up, set the trip on the odometer to 0, and keep a full gas can in the back. Drive it til it runs out of gas and see how many miles you get. That'll at least give you an idea of whether you're actually low on gas or not. You should have an 18 gallon tank, and these things usually get around 17mpg, so you SHOULD get somewhere around 300 miles per fill up. I mean, this doesn't fix the problem, but oh well. I drove my truck for about a year without a fuel gauge. Being stuck out in the middle of nowhere without any gas makes you learn to keep track.. take my word for it haha