Faulty Fuel Gauge
07-19-2023, 04:16 PM
#1
New Member
Thread Starter
Faulty Fuel Gauge
No this isn’t a post about me filling up and the fuel gauge showing 3/4 tank full. I’ve only come across this issue when I was driving on the highway and car started bogging and so I pulled to the side and shut it off. Tried starting it back up…nothing, crank no start. The fuel gauge read HALF when i was driving home. Pushed it to a rest stop and a road ranger took a look at it and did the most sketchy s***. Not gonna say it. It worked and turns out I don't have fuel in the system. 2 weeks later drove home from work and car bogged and cranked no start, gauge read a little over half and this is me driving like a law abiding citizen, just 5 over the limit. So I changed out the floater on the driver side since the Z has two, I thought maybe it’s just one that’s faulty so I changed that. Filled it up- drove for 1 week (a little spirited) and noticed it doesn’t go under half so I still have some options. 1.) Replace the floater on the fuel pump. 2.) Replace the fuel pump assembly. 3.) Contemplate if it’s a wiring issue in the cluster. 4.) scrap the car.
07-19-2023, 07:03 PM
#2
Since you already replaced one of the fuel level senders (driver side), just replace your main fuel pump assembly on the passenger side. An OEM Hitachi replacement complete unit (which includes a new level sender) is surprisingly cheap! The prices online range from $160 to a little over $200. I would recommend picking up a new O-ring seal. It's not very difficult to replace the pump assembly, plenty of videos cover this.
Also, since you've already run the vehicle low/dry on fuel more than once, I would replace the fuel pump as preventative maintenance anyway, these pumps do not like to be run dry and will burn out if you crank the engine with only fumes in the tank! I've never heard of stepper motor or wiring issues with 350Z gauge clusters, in short, it's highly unlikely that you have a bad gauge cluster. If you pull up the wiring diagram, you can use a multimeter to check the resistance specs on the passenger side level sender to confirm it's bad or not.
Usually I don't like to replace parts unless I have done some basic testing to verify the fault. But in this case I think it's a safe bet your sender unit on the passenger side is acting up. I believe the cluster takes the average reading from both level senders to set the gauge needle value. Years ago I remember someone writing a post on these forums about the floater arm copper contacts getting gummed up or corroded. They made a detailed post about cleaning up the contacts for the level sender float arm and it fixing their faulty fuel readings. So that's a potential free fix with just your time and some sand paper.
Cheers!
-Icer
Also, since you've already run the vehicle low/dry on fuel more than once, I would replace the fuel pump as preventative maintenance anyway, these pumps do not like to be run dry and will burn out if you crank the engine with only fumes in the tank! I've never heard of stepper motor or wiring issues with 350Z gauge clusters, in short, it's highly unlikely that you have a bad gauge cluster. If you pull up the wiring diagram, you can use a multimeter to check the resistance specs on the passenger side level sender to confirm it's bad or not.
Usually I don't like to replace parts unless I have done some basic testing to verify the fault. But in this case I think it's a safe bet your sender unit on the passenger side is acting up. I believe the cluster takes the average reading from both level senders to set the gauge needle value. Years ago I remember someone writing a post on these forums about the floater arm copper contacts getting gummed up or corroded. They made a detailed post about cleaning up the contacts for the level sender float arm and it fixing their faulty fuel readings. So that's a potential free fix with just your time and some sand paper.
Cheers!
-Icer
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dvd.z33 (07-19-2023)
07-19-2023, 07:37 PM
#3
New Member
Thread Starter
Since you already replaced one of the fuel level senders (driver side), just replace your main fuel pump assembly on the passenger side. An OEM Hitachi replacement complete unit (which includes a new level sender) is surprisingly cheap! The prices online range from $160 to a little over $200. I would recommend picking up a new O-ring seal. It's not very difficult to replace the pump assembly, plenty of videos cover this.
Also, since you've already run the vehicle low/dry on fuel more than once, I would replace the fuel pump as preventative maintenance anyway, these pumps do not like to be run dry and will burn out if you crank the engine with only fumes in the tank! I've never heard of stepper motor or wiring issues with 350Z gauge clusters, in short, it's highly unlikely that you have a bad gauge cluster. If you pull up the wiring diagram, you can use a multimeter to check the resistance specs on the passenger side level sender to confirm it's bad or not.
Usually I don't like to replace parts unless I have done some basic testing to verify the fault. But in this case I think it's a safe bet your sender unit on the passenger side is acting up. I believe the cluster takes the average reading from both level senders to set the gauge needle value. Years ago I remember someone writing a post on these forums about the floater arm copper contacts getting gummed up or corroded. They made a detailed post about cleaning up the contacts for the level sender float arm and it fixing their faulty fuel readings. So that's a potential free fix with just your time and some sand paper.
Cheers!
-Icer
Also, since you've already run the vehicle low/dry on fuel more than once, I would replace the fuel pump as preventative maintenance anyway, these pumps do not like to be run dry and will burn out if you crank the engine with only fumes in the tank! I've never heard of stepper motor or wiring issues with 350Z gauge clusters, in short, it's highly unlikely that you have a bad gauge cluster. If you pull up the wiring diagram, you can use a multimeter to check the resistance specs on the passenger side level sender to confirm it's bad or not.
Usually I don't like to replace parts unless I have done some basic testing to verify the fault. But in this case I think it's a safe bet your sender unit on the passenger side is acting up. I believe the cluster takes the average reading from both level senders to set the gauge needle value. Years ago I remember someone writing a post on these forums about the floater arm copper contacts getting gummed up or corroded. They made a detailed post about cleaning up the contacts for the level sender float arm and it fixing their faulty fuel readings. So that's a potential free fix with just your time and some sand paper.
Cheers!
-Icer
07-20-2023, 04:46 AM
#4
Possibly related or maybe not, but the inaccurate fuel level on the cluster is also a fairly common problem in the G35 as well. Sometimes it's related to dirty contacts on the floater arm as previously mentioned, but others have replaced that and still gotten inaccurate readings on the cluster. The problem turned out to be the cluster itself and a result of some corroded connections. There are lots of mail-in services out there that will repair the stepper motors and clean up any bad soldered contacts. If you notice any dim or flickering lights in the cluster, this could possibly be it.
07-20-2023, 09:10 AM
#5
New Member
Thread Starter
Possibly related or maybe not, but the inaccurate fuel level on the cluster is also a fairly common problem in the G35 as well. Sometimes it's related to dirty contacts on the floater arm as previously mentioned, but others have replaced that and still gotten inaccurate readings on the cluster. The problem turned out to be the cluster itself and a result of some corroded connections. There are lots of mail-in services out there that will repair the stepper motors and clean up any bad soldered contacts. If you notice any dim or flickering lights in the cluster, this could possibly be it.
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