20 Most Recent 2004 Mercury Grand Marquis - Page 7 Questions & Answers

You have to ask yourself if you really really want to fix this.There's a float and potentiometer inside the gas tank. If the float is getting blocked from floating all the way up or the potentiometer is only going so far up, that would create this problem. The whole assembly is called the "gas tank sending unit".The tough part is that you probably have to drop the gas tank to replace or fix these items. It's rare that cars have access holes under the back seat for this.