Fuel gauge not registering full

[kamiguy]

I have about 12k on my 2008 EX35 and recently the fuel gauge doesn't indicate full after filling. It shows about 1/8th down and after some driving eventually shows full. This is a new development and it doesn't matter how slowly I fill the tank. I had an Nissan X-Trail before and it had the same symptoms too. Is this a Nissan thing?

[googleman]

I had a ford in the past that did the same thing. I don't know the exact reason. Have you ever run out of gas with your EX?

I have about 12k on my 2008 EX35 and recently the fuel gauge doesn't indicate full after filling. It shows about 1/8th down and after some driving eventually shows full. This is a new development and it doesn't matter how slowly I fill the tank. I had an Nissan X-Trail before and it had the same symptoms too. Is this a Nissan thing?

[kamiguy]

Never ran out of gas. Just seems to be a slowly developing thing with the 2 Nissan products I had recently. I wonder if they use the same fuel tank sender across their product line?

[dividedhighw]

Mine never did that - I would have it looked at under warranty, ASAP.

[KJ911TT]

Never ran out of gas. Just seems to be a slowly developing thing with the 2 Nissan products I had recently. I wonder if they use the same fuel tank sender across their product line?

I had this problem with my 2005 FX45. I never got it fixed and just returned it after the lease was finished like that.

- KJ

[SteveTheTech]

Have you been refueling with the key on? How much premium are you getting in there?

This is a hard one to pinpoint sometimes. The issue is usually either one of the sensors (mounted in the center of either side of the tank) or the combination meter, as those are the two primary components of the system. All of which I have been updated since previous models. Personally I have not seen an issue with either of these parts causing an issue on the American models in my area. A google search may bring up some Infiniti gauge issues on other models and although the EX is similar to the Y34 and early FM model cars there is a big difference in some small things internal software algorithms within the combination meter is one of them.

-Interesting EX tidbit- The combination meter in the 07+G and EX were designed and built by the supplier for Audi. Not that that is a bad thing many of the parts are outside sourced and if you think about it they source parts from companies that do it (whatever it is) well in most cases.

Now that being said there may not actually be an issue persay and the amount of time it takes to register full can vary depending on how the fuel migrates to the other side of the tank, ambient temperature, inclination and a whole host of other possibilities. If the gauge eventually reads full that actually means the system is indeed working and the combination meter internal computer is designed to slow the output of the gauge to remove sloshing readings like many older cars.

[kamiguy]

Thanks for the info, all. It seems I am not alone with this issue. Google turned up a lot of info about various Infiniti models having this problem. I am getting the correct amount of fuel in at the pump so looks like it's time to talk to the dealer but won't be till later in the year as I just had a service done and it's a 2 hour drive there. But I will try a trick another poster mentioned on a different forum. After the pump clicks off, he removed the nozzle then reinserted and topped it off. So even though I think I am getting the right amount of fuel I might be able to put a few more litres in (Canadian, eh). But the fact still remains that there is a defect with the car since I have always filled up the same way.

[SteveTheTech]

There is no magic trick to fool the car. The On Board Vapor Refueling System is designed to operate on a very small amount of negative air pressure in the fuel tank and filler neck to send a small signal to the fuel filler nozzle to cease flow. Re-inserting the nozzle and retrying will work sometimes if there is an issue with the pump.

Really the check and see how many liters your car takes next time. The tank holds 76 Litres (20 gallons). Using a little math you can see if the tank is actually filling the majority of the way. Keep in mind there needs to be an air gap and you will never actually "fill" the tank.

Wait are we talking about the tank not filling or the gauge not registering? Those are two very different issues and I don't know why they tend to come up in conversation at the same time.

[kamiguy]

Yeah we got off on a tangent there. Of course it could be a cause and effect thing.. is the gauge defective or is the tank not allowing itself to be filled completely? If it's the tank.. what could cause that? I do notice that I don't seem to have the range in the city that I used to yet the fuel economy seems to be the same. Hmmmmmmm

[Timmbo]

I had that happen on my Armada, Nissan replaced a Fuel Control/Information Unit under warranty.

[aft981]

Steve,

This reminds me, I've been meaning to ask for a while. I thought the tank was supposed to hold 20 gallons, everywhere I've read (manual, infiniti.com, reviews) states it holds 20 gallons, and you also just said that. However, on countless occasions I've filled it and I've put more than 20 gallons in. The most I put in once was 20.58 gallons. Could it actually be 21 capacity?

[googleman]

My sense was there is some sort of reserve not included in the listed 20g capacity. Although I personally got quite close to 20 gallons couple of times when I was filling the tank, I never exceeded it.

How many miles after the fuel indicator light are you able to fill more than 20 gallons? Is it always from the same gas station?

Steve,

This reminds me, I've been meaning to ask for a while. I thought the tank was supposed to hold 20 gallons, everywhere I've read (manual, infiniti.com, reviews) states it holds 20 gallons, and you also just said that. However, on countless occasions I've filled it and I've put more than 20 gallons in. The most I put in once was 20.58 gallons. Could it actually be 21 capacity?

[jmess]

Any change in fuel brands? Some GM based mythology blamed the sulfur contend of gas as causing problems with sending units in GM fuel tanks.

My 05 vette's fuel gauge failed when I drove off the dealer's lot, made it 500 feet after signing the papers. They had to replace the slider unit inside the tank (actually had two tanks). Many of the vette pundits couldn't accept the notion that GM could screw up something as basic as a fuel level sensor and swore the problems were caused by high sulfur content fuel.

[Timmbo]

Sending unit, that is what they replaced in my Armada.

[kamiguy]

Nope.. same brand and usually the same pump too! Gonna let it get dry then fill up and at least make sure I am getting my 76 litres, or at least close to it. Must be getting a full tank at fill-up...can't see how I could get less so it must be the sender.

[SteveTheTech]

Basically if there is an issue determining if the tank is being filled it is crucial to know how much fuel it is taking before shutting off. If the car is taking almost 20 gallons (75 liters) or more (see below) depending on the level at the time of refueling and the gauge is not registering that tends to be an issue with the gauge.

If the pump cuts off several times while trying to refuel that is an issue in the On Board Vapor Recovery system and is near impossible for us to diagnose since the majoirty of the parts are located inside the tank. In previous models there was an updated shutter valve at the bottom of the filler neck tube that required us to put our hands into the tank full of fuel an razor sharp aluminum dividers (to prevent sloshing) to access the neck. If it's got to be done it's got to be done. These types of things tend to appear in a limited number of models and even models in close VIN order may not experience the same issue.

If the gauge doesn't read correctly and the tank is full it may also be a sign of an inaccurate reading in one of the level sensors. These variable resistors use a float arm and a resistor strip, this is the same design that everyone has been using for years. The calculation between the two saddles is made by the combination meter and if one of the inputs is off the computer will incorrectly reflect that. This is not so easy to detect sometimes.