I bought a 2004 350Z in June. I noticed right away the gas gauge was very inaccurate. I have done a lot of searching on the internet and this forum and found that the resistor elements in the sending units were getting contaminated and increasing the resistance of the elements. I have read about pulling the sending units out and cleaning them, and this fixed the problem. I was reviewing the videos for the repair in preparation to clean them. Then I thought about it. If you can pull the units out and clean them with a solvent, then why can’t you clean them in the tank with a solvent?
I put in a can of fuel system cleaner with around 8 gallons of gas in the tank. I figured this by the mileage on the odometer since the last filllup. The gauge registered just above 1/4 tank.I then drove it around 10 miles and filled up. The needle on the gauge was about the width of the needle above the full mark. Before it was between the full and 3/4 marks when filled. It would quickly drop after that. I drove another 10 miles and put in another can of cleaner.
This is real soon after putting in the cleaner, but I have driven 44 miles since filling the tank and the needle is just barely below the full mark. Before it waould have been down to 3/4. It is now behaving as I would expect. Again, this is only after 44 miles, but I’m confident this has fixed the problem. It’s never registered properly before.
The cleaner I used was from Walmart. I compared the ingredients and instructions to the more expensive brands and it looked the same. I used Super Tech Motor Treatment. I would have waited a while to post this, but I was anxious to get this information out to hopefully keep others from pullilng out the sending units if it’s not necessary.

 

I will try this, but I don't drive that often so it might take 6 months to go through a tank of gas. My gauge reads half after using 5 gallons and empty with about 7 gallons left in the tank.

 

I put a full can of cleaner in with around 8 gallons of gas. I then drove it around 10 miles to slosh the gas and cleaner around to hopefully clean the sensors. After 10 miles I filled the tank and it was working right. The cleaner should work very quickly for you. The gauge didn’t move off 1/4 during the drive. It may be that the cleaner couldn’t get to the parts of the sensor that were making contact until the extra gas lifted the sensor up.

 

I now have 150 miles on the tank after adding the cleaner. The fuel gauge is tracking great.

 

Great info. I have this problem, but intermittently... so I haven't done any significant repair. I will try your fix ad report back on this (your) thread. Thanks for posting.

 

Hi op, which gas station did you normally go? I had the same problem too. Everytime i fill the gas, i can only fill like 5 or 6 gallons but the gauge only show 1/4, the DTE shows around 100 miles. That so annoying and makes me go to gas station every 2-3 days. I tried the fuel cleaner once and still didn't fix the problem. I fill with 91 but always trying to find the cheapest gas i can find.
But last time, i gave a shot and went to shell (i remembered about their ad that saying they have better additive something like that lol). Same thing, i can only fill like 5-6 gal and the pump stop. Then i start the car and... boom... the gauge reading full. I was so happy that time that shell gas fix the problem (i hope). now i'm planning to try chevron next time

 

Epenpecks. Good information. It looks like fuel system cleaners are the solution to the problem, whether adding a can or using gas that includes it.

 

I just bought the car in June with 45,000 miles on it. It’s an 04. I don’t know where they filled up. I typIcally fill up at Sam’s club. If I have the problem again I’ll try Shell instead of an additive. It will be cheaper doing that. Good move on your part.