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Discussion Starter #1
lots of issues lately...


after the fx was in the shop all day getting the door handle worked on it had 1/4 tank. as I was driving I watched the fuel gauge slowly dip down to the peg, showing completely bone dry. I stopped on my way home, put in 20L but still nothing on the gauge. Later that night I filled it up completely. Still nothing on the gauge. The display shows "---" miles to empty


I've seen a lot of talk of 1st gen fx's having fuel gauge issues, not too much with 2nd gen. Any insight? is this a remove sender and clean issue, or maybe a reset with scanner issue? rockauto lists a sender and a pump, are they separate or is there two senders?

thanks!
 

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Try cleaning first but you may have to replace. I believe the 2nd gen has two senders like the 1st.
 

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Discussion Starter #4
yes rock auto lists a separate fuel pump/sending unit and sending unit. infiniti parts shows the same, though they also sell the passenger side sending unit separate from the fuel pump (naturally this costs more than the pump/sending unit from rock auto)

I'm curious about how the two sending units work together (electrically/logically speaking) and whether a person could tell which one has failed, short of replacing.

will update once I have some time to tear into it.
 

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It's been a long time since I saw detailed posting but I seem to recall that the float unit in one or both fails. You may be able to find this problem when you inspect them.
 

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Discussion Starter #6
I used the directions and multimeter readings from this thread
https://www.infinitiscene.com/threads/gas-gauge-level-fix.36355/

I removed the driver's side sending unit, measured the output ohms and it seemed within spec and changed as I moved the float. The tines didn't look to be dirty at all, but I ran an eraser over them. Reinstalled, started vehicle, fuel gauge still empty.

I loosened the passenger side sending unit/pump but struggled a bit with removing the pickup hose so I measured the outputs while it was kind of half in the tank. I measured the output ohms and it also seemed to be within spec and changed as I moved the float. it's POSSIBLE that the float was jammed in the down position. When the gauge first went wonky I believe I was at about 1/4 tank of fuel, and I was parked at a distinct uphill slope, and I watched the fuel gauge drop (thought at the time that it was just because of the angle)
I reinstalled the sending unit/pump and started it up, gauge started working. Spun around the block, then went to the gas station to fill up. gauge went to the top like normal.
I guess we'll see how long it lasts, hopefully this is the last of it!

FTR this was a pretty easy task for someone with reasonable amateur mechanical ability
 

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Nicely done Chris. Let us know how it holds up but if the problem returns I guess you will have to change the passenger side sending unit
 

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I've had a fuel gauge issue with my 2011 FX50s since I got it a couple years ago. Replaced both sending units/fuel pump and the instrument panel, yet the problem remains. Just picked up the AC Amplifier unit, and will be installing shortly. Wish me luck. This thing has been driving me to drink.
 

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what issue have you been having? why do you believe the AC Amplifier unit is related to fuel gauge?
My FX runs out of fuel anywhere between half a tank and a quarter. I've replaced everything else, and there are a couple folks on the G37 forum who replaced the AC Amp unit, and it rectified the issue. Apparently a bunch of stuff goes through that unit. I picked up a used part for $40, and only took an hour to install. I figured it couldn't hurt, and I've tried everything else.
 

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Discussion Starter #11
My FX runs out of fuel anywhere between half a tank and a quarter. I've replaced everything else, and there are a couple folks on the G37 forum who replaced the AC Amp unit, and it rectified the issue. Apparently a bunch of stuff goes through that unit. I picked up a used part for $40, and only took an hour to install. I figured it couldn't hurt, and I've tried everything else.
hopefully it helps, keep us posted!
 

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Discussion Starter #12
this weekend I was just under half tank, per the guage. I parked on a moderate grade for about 10 minutes, and when I started the vehicle up it went to zero fuel on the gauge. $&#*.

Drove around on my errands, parked for a bit on level ground, started it up, gauge back to normal. I wonder if the float in one of the tanks get jammed down when that tank is empty. anyway, I'm glad I didn't have to monkey around inside the fuel tank again!
 

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Discussion Starter #15
happened again, fuel was around half a tank. didn't fix on its own this time. I jiggled the passenger side pump/float a bit and it's back to working. mildly annoying, but it only took 8 minutes to fix.
 

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I had the same problem.it accures when i fill it very low for example its empty and fill 20 litres of petrol. And it begins to show empty and i discovered that when i fill more than 50 litres it works properly.and dont let it to get very low of petrol

Sent from my MI 8 using Tapatalk
 

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interestingly I found a TSB about this while looking for something completely different

Well, I can say I replaced my sending unit with new to no avail. I pulled the other fuel pump sending unit assembly, etc. Let it dry, took an eraser to it and reinstalled...nothing. Took it to fill it up just a few minutes ago and its working like new again. I did drive it down to about 1/8 tank before I started working on it though.
I never touched the springs on the pump/sender at all. Just air dry and an eraser and replaced sending unit on opposite side for what its worth.
 

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Well, I can say I replaced my sending unit with new to no avail. I pulled the other fuel pump sending unit assembly, etc. Let it dry, took an eraser to it and reinstalled...nothing. Took it to fill it up just a few minutes ago and its working like new again. I did drive it down to about 1/8 tank before I started working on it though.
I never touched the springs on the pump/sender at all. Just air dry and an eraser and replaced sending unit on opposite side for what its worth.
I literally dis it today and it worked.....so who knows.
 

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Discussion Starter #20
my passenger side float is getting jammed on the bottom of the tank, I'm convinced of it. Every once in a while when the tank gets around half full the gauge will just drop to empty and won't go up if I fill the tank. I pull the rear seat, disconnect the electrical from the pump/sending unit, lift it up an inch and wiggle it up and down, reinstall, reconnect, seat back in, gauge is fine. One thing I haven't tried (and I will next time it comes up) is just disconnecting the pump/sending unit electrical without wiggling the float. Mild annoyance when compared with the doors freezing shut, but easy to overlook after a nice third gear WOT pull.
 
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