Just bought this from a used car dealership, and I am ticked off already. Gas guage not working and check engine light after 50 miles driving. Brought it back to dealer who swapped out the fuel sending unit, now gauge is moving from F but appears to be moving to slowly for amounf of miles put on, and check engine light back on with smell of gas (which I was told was because when they swapped the sending unit some gas fumes get into car). After 2 days the fumes are still there and the code is P0445.

-Could they not have sealed up that area correctly (missed an o ring or something) that would cause smell and that code?

-NY Lemon law, would it cover the fuel components or just the fuel pump?

Finally what would you do? I signed all papers, put money down but the finance company did not pay dealer yet. Would you have them hold off until its fixed properly?

If the finance company is willing to do that for you, I would drop it off and tell them to call you when everything is fixed. Probably wouldn't hurt to take it to an independent mechanic and have him check it out thoroughly before you drop it off to see if there is anything else wrong with it. Your best to speak with an attorney regarding Lemon Laws in your state. Same states give 2-3 days to cancel the deal, so don't drag your feet! It's possible to have a residual gas smell for a couple of days. The fuel sender is accessed through a panel under the rear seat. The evaporative emission trouble code could be caused by a poor seal at the sending unit, but also due to a problem with the evaporative emission system, which in itself could cause gas odors if not working properly.

So the check engine has not returned, the smell is all but gone. The o-ring was shot and replaced. Fuel gauge still seems off, I think the gauge connectors need a good cleaning and will have done next.

I doubt that it's the gauge connections. If the reading is off, it's likely the sending unit needs to be adjusted. Some Nissan sending units have an adjustment on them; if not, the float arm has to be bent slightly. The problem is the gas tank would need to be removed again to do this.

Thank you for the heads up. So does this sound about right: a bent float means a shorter float, so full is full, but as the fuel hits a certain level the float does not reach and gives an incorrect reading.

So the fuel sending unit can be accessed by the rear seat, but the actual float requires the tank to be dropped?

My bad..forgot this was an R50! Yes, you can access the sender below the rear seat, so there's no need to drop the tank.

As the fuel in the tank raises or lowers, the float goes up or down, respectively. The float is attached to a wire which pivots on the sender. This action changes the resistance is the circuit to ground, which is shown at the gauge.

Some Nissan fuel senders will have the sender in a toothed track, so it can be adjusted up or down slightly, whereas others do not, so the wire arm that hold the float needs to be bent to make an adjustment. If the tank is full but is not showing completely full on the gauge, the float needs to be positioned lower. If the tank is near empty but showing more than empty on the gauge, the float needs to be positioned higher.

To test the function of the fuel gauge, the wire at the sending unit from the gauge can be shorted to ground, which should cause the gauge needle to raise to the "full" position. When the wire is not grounded, the needle should go to the "empty" position, obviously.

The gauge is "working" now, it goes to full, however, it drops very slowly and I know I am not getting 400 miles per tank plus. My first test I was getting around 17mpg. I don't know electronics, but to me this sounds like a more mechanical issue, like maybe the fuel level arm on the sender needs adjustment, or is maybe gummed up and not functioning. Will take it out and see If I can adjust and clean it off.

thanks again.

Can the gauge ever be the issue? I just had my shop replace the sending unit, and it seems to act just the way it did before, which is to say the tank stays on full too long, and when it gets to 1/3 of a tank, is actually empty. I don't know for sure yet, since I filled up right after the repair and haven't driven it down yet.

It was funny though, I was trying to run it out of fuel (at least as low as I could get it) before bringing it to the shop. I was at the intersection just before pulling into the shop and it died. i was on an incline. Gauge showed 1/3 full. Rolling through the intersection in neutral and was able to start it when I got into the intersection.

When the shop put it together after the repair they said, hey, it shouldn't have dies you have 1/3 of a tank in there. Of course, that's where it was when I brought it to them. I took it one block to a gas station. Filled tank with 18.9 gallons. Apparently these tanks hold 21.1 gallons so I had just two gallons in the tank. Definitely not 1/3 of a tank but with 2 gallons it shouldn't have died either. So, gauge? Fuel sender adjustment? Or do I have a fuel pump issue?

Gauge reading relies on the resistance created in the ground circuit in relation to the position of the float arm and the sender. When fuel gauges fail, they usually either don't work at all or won't read the full range of the gauge from high to low. To check the gauge operation, you need to disconnect the appropriate harness connector on top of the fuel sender and identify the correct wire from the gauge using a wire diagram. With the key off, ground the wire in the connector to a clean, chassis ground. Turn the key on, and the gauge needle should slowly go from empty to the full mark. If it doesn't, you likely have a faulty gauge, but should check for resistance in the wire from the fuel sender harness connector to the back of the cluster just to be sure. If the needle runs the full range properly, it is likely the issue is not with the gauge.
Some Nissan sending units have an adjustment provision (L30 Altimas come to mind) and some do not, meaning you have to adjust the float arm in order to adjust the sender. If you are bending the arm, do so in small adjustments. With the sender removed and plugged into the harness connector, position the float arm all the way to the bottom and and turn the key on; the gauge should be reading empty. Move the float arm to the top of it's range and the gauge should slowly rise to the full mark. This will at least tell you that the float arm and it's contact with the resistance grid of the sender is working good. Actually adjusting the sender to the fuel level in the tank is a little trickier and can become tedious. You may have to R&R the sender several times for adjustments, keeping in mind the relation of the float arm adjustments to what you are trying to accomplish with your gauge reading. Those with adjustment provisions will have a slide assembly in the sender with fine, plastic teeth that hold slide in position on the sender. Moving the slide up or down results in moving the float arm assembly up and down, respectively, which is nice because it keeps the proper float arm geometry, something that is a lot more difficult with the provision because you have to manually bend the float arm on those models. Fortunately you do have access to the sender without dropping the fuel tank! That saves a lot of work and headache!
The fuel pump has nothing to do with the gauge reading.

My shop is once again looking into the issue because when I got it back it was the same; that is, reading 1/3 full when it was near empty. Shop owner seems to think replacing the instrument cluster would fix the problem, but at a heavy cost. New ones are over $700, and used ones are a difficult find. Still not ideal because swapping out the instrument cluster means I'll end up with an inaccurate odometer. I'm of a mind to think that adjusting the float arm up just slightly would cause the gauge to read more accurately and might be the easiest solution. I believe this could be the answer because when full the meter is absolutely pegged and doesn't more off of the full mark for some time. I think overall the gauge is working correctly but the readings are just a bit out of whack, just a bit high.

Clusters can be sent out for repair for a lot cheaper than $700; new clusters from Nissan are programmed with the mileage. I would be highly suspect that the cluster is the problem, however.

I gave up on the issue. I reset trip mileage odometer after every fill up, when I get to X I fill up.

I did complain to Nissan corporate as it seems this is a common issue. When I get the equipment I will remove the sending unit and do the test you see on youtube.

I don't think its the sending unit causing this issue, I am on #2, and find it really hard to believe 2 random units have same issue. I think its wiring/cluster issue.