Hey everyone, I recently picked up a 07 G35x and I'm having an issue with the fuel gauge (before anyone jumps to cleaning the fuel sending units, see below). It's consistently reading a quarter tank too high.

I did take it apart and found that the sending units were clean but I did a once over just to be sure; no change on the gauge.

I also noticed that my driver side of the tank was nearing empty however the passenger side was nearly full, I'm not sure if it should be like this (?) I know it uses a saddle style tank with a venturi effect to even out the levels.

I also did test the sensors manually with them out of the car. The voltage on the driver side was fine but the passenger side did not seem linear when moving the float.

I plugged the sensors in and put the car in run mode with the senders out of the tank (both driver and passenger side), and when both floats were at the lowest position, the gauge was still reading 1/4 tank.

Has anyone encountered a gauge situation like this? The instrument cluster also tested out ok, do you guys think its the passenger side (fuel pump assembly with sensor) or could it be the AC amplifier?

 

I have 2 sending units in my 07 and i remember i had the overflow issue as well due to the crossover pipe not sealing correctly on the pump module. There is an o-ring on that tube and after replacing all o-rings, my tank is able to equalize now and fuel level shows fine. This car reads both levels and gives out the average when the tank is equal and if not, then it will give out the lowest reading, at least that was my case..

 

Are you talking about the "crossover pipe" the black braided hose coming from the tank going into the side of the fuel pump assembly? I had disconnected two hoses when taking my fuel pump out; one was the main hose on top of the fuel pump assembly and the other one was the black hose going inside the tank.

I have been reading about some "jet pump" that's responsible for distributing gas between both sides of the tank.

Would a whole new fuel pump assembly fix this issue? Thanks

 

That braided tube is the one that equalizes both sides. Unhook it and replace the o-ring on the pump module side, make sure it's fuel rated o-ring and of good size so when you'll be pushing it back in to lock it, it should feel tight. Otherwise, if there is a break in liquid vacuum, fuel won't be pulled from passenger side..

 

Thanks for the tip, would missing O-rings under the locking ring (both passenger and driver side) by the sending units also mean the pump won't be able to vacuum gas?

Thanks again

 

No, those just keep dirt out.

 

Quick question, for the fuel return line O-ring, which one did you use? I can't seem to find one sold individually, would a fuel injector seal/O-ring work?

Thanks again

 

Go on amazon, search for fuel orings, measure the inside diameter of the cross over tube and outside diameter of the fuel module pipe then find your orings. There is no direct fit so find closest one just make sure they're fuel rated.

 

Greetings. I have great experience with the infamous fuel gauge problem on Infiniti G35X. My daughter had a 2008 G35X that I absolutely loved so I spent a lot of time working on her car until she locked up the engine and we just recently scrapped the car in June 2025. For the first several years of her ownership of her car, the fuel level reading on the gauge on the front instrument cluster was never reliable, and she ran out of gas on at least three occasions. I cleaned the existing fuel sending units, but that didn't help. I replaced them with used OEM ones that I pulled off another G35X at a junkyard, but that didn't help. Then I replaced them with used OEM ones that I bought from somebody on ebay, but that didn't help. Next, I refocused on the instrument cluster. I removed the instrument cluster from her car and took it to two guys that specialize in instrument cluster repairs in their basement shop. They couldn't find anything wrong with her instrument cluster. I bought a used OEM instrument cluster on ebay and installed that one, but the inaccurate fuel gauge persisted. I spent countless numbers of hours searching the internet and this forum in search of the answer. I was dumbfounded how many G35 lovers have suffered with the same problem, but I could never find a solution. I bought access to drawings from Infiniti and finally deduced the potential problem to a heat amplifier control module (p/n P:27760 JK700 that is mounted on top of the center stereo module. I spent countless more hours trying to locate a new one of those modules. I would frequently check with local junk yards and ebay and google in search of one. After several months my persistence paid off because I found a used OEM one. It only took me about 30 minutes to install it. I wish I video taped the procedure. Once I installed the used OEM AC Heat Amp Control Module P:27760 JK700, the fuel gauge worked correctly for the next 4-5 years until we scrapped the car . Before the tow truck arrived, I pulled that module moments only before the tow truck arrived because somebody out there needs it, and you'll be lucky to find another! The attached four photos beginning with s-l1600 are the actual ones from the ebay posting where I found the used module. The fifth photo entitled "Infiniti G35X OEM AC Heat Amp Control Module P 27760 JK700" is the module as fitted on the computer assembly that I removed from my daughter's car. Trust me, this is the answer. I've never used this forum before and I haven't investigated how to DM yet and I'm hesitant to post my name, email address, or phone number yet because I don't want to attract spam, but if somebody out there who has been enduring the fuel gauge problem who is mechanically inclined and ambitious enough to finally fix it, feel free to drop me a message. I have the module and I could probably point you in the direction of a YouTube video that shows you how to remove the center computer that is tucked behind the stereo button panels. Rgds, Andrew