HELP! 04 350 big problem with my fuel gauge

[quietkilla6]

i was driving on the high way the other day when all of a sudden my fuel (POD? CLUSTER? gauge?) started reading that i was getting 0.4 miles per gallon... then i went and filled my tank and it only read that i filled it up 3/4 of the way when i most definitly topped off... and now that this is happening it seems like im useing fuel faster but i might be assuming that because i cant see my first 1/4 of my tank... ANYONE have this happen before? REASON?

[504 350z]

i was driving on the high way the other day when all of a sudden my fuel (POD? CLUSTER? gauge?) started reading that i was getting 0.4 miles per gallon... then i went and filled my tank and it only read that i filled it up 3/4 of the way when i most definitly topped off... and now that this is happening it seems like im useing fuel faster but i might be assuming that because i cant see my first 1/4 of my tank... ANYONE have this happen before? REASON?

i have been having the same problem in the past month with my 07. i top it off with gas and the fuel only reads 3/4 of the way full. i have no ryme or reason for this.

[samej82]

i have been having the same problem in the past month with my 07. i top it off with gas and the fuel only reads 3/4 of the way full. i have no ryme or reason for this.

Do you shut the car off while it's refueling?

[504 350z]

actually i had the car off but my lights on.

[samej82]

Well it's still under warranty.. I'd fill it up two more times and then take it in I guess.

[samej82]

i was driving on the high way the other day when all of a sudden my fuel (POD? CLUSTER? gauge?) started reading that i was getting 0.4 miles per gallon... then i went and filled my tank and it only read that i filled it up 3/4 of the way when i most definitly topped off... and now that this is happening it seems like im useing fuel faster but i might be assuming that because i cant see my first 1/4 of my tank... ANYONE have this happen before? REASON?

Did you modify anything with the exhaust or computer right before this happened?

[quietkilla6]

i havent had any mods done personally but i bought the car used so i dunno if the person before me did anything to it but it seems like when i drive next to other zs im always faster even when im not trying to race so i think that it might be chipped. or im just a ganster on the pedels haha

[quietkilla6]

i always turn everything off when fueling because i fuel jets and ive learned alot about fuel explosions in the last couple months, you wouldnt believe the stories ive herd that just make never want to get gas haha

[NomisST]

I've been experiencing this as well recently. Every time I go to the gas station now, I say fill up when the low fuel light is on and it only gives me like 7 gallons. The guy that works at the gas station had to force more into the tank, even he knew that it wasn't filled. Before that I use to fill up to 15 gallons, which is also weird since the tank is like 20 gallons. I feel like the 350 probably has a HUGE reserve tank. Anyone else have this problem?

[simplewon]

The Z does not have a vent to the filler neck area as most cars, instead, it uses a pressure sensor. The sensor detects pressure in the fuel tank and then opens a solonoid to vent the tank when fueling. The sensor and solonoid are located on the carbon/charcol canistor which is located behind the rr tire just inside the bumper. If the pressure sensor is weak, it will kick the pump off early. Ez to bypass. Difficult for the dealer to figure out. It can create a code if failure is severe enough but probably won't.

[NomisST]

What do you mean by Bypass? Is this a simple fix or something? Please let me know more!

[rmezz13]

You know what i have this problem from time to time, if you slow the pump down after it kicks off the first time it should fill up all the way...... I just figured the pump was pumping to fast for that car (when i got it) and slowed it down and i can fill it all the way every time. Takes maybe a minute longer to fuel up.

[NomisST]

I actually live in NJ, one of the only states where you're not aloud to pump your own gas...it's so weird...

[R350Zz33]

the z also does have a very large reserve i think its like 7 gallons so it has a 20 gallon tank so on the fuel gauge fule to empty is about 13 gallons and when ur fuel light goes on u got about 6 or 7 gallons left but with ur problems about ur gauges go to the dealer and if its still under warenty make them fix it if it was me i would stay untill they fixed it. make an appontment and get there bright and early

[simplewon]

Locate the charcol canister, it's to the right(passenger side) of the stock muffler. It has a heat shield covering it. Held by three screws. Quarter inch rachet, extention and universal swivel is helpful. There are three hoses connected to the canister, one from the vent on top of the tank, one to outside air, ends just behind the rear differential and the last one goes to the intake manifold. Just disconnect the one from the tank, has strong fuel odor, and disconnect the vent that vents to outside air that ends near the rear differential and connect the two hoses together.

[NomisST]

Locate the charcol canister, it's to the right(passenger side) of the stock muffler. It has a heat shield covering it. Held by three screws. Quarter inch rachet, extention and universal swivel is helpful. There are three hoses connected to the canister, one from the vent on top of the tank, one to outside air, ends just behind the rear differential and the last one goes to the intake manifold. Just disconnect the one from the tank, has strong fuel odor, and disconnect the vent that vents to outside air that ends near the rear differential and connect the two hoses together.

Wait, what does this do exactly? If they weren't connected in the first place why would you connect them?

[simplewon]

If they are not connected, there will be no place for air/vapor to escape the tank while filling which will kick the pump off. With the key in the on position without the engine running, the vent solonoid on the canister is supposed to open. If the key is off while filling the pressure sensor in the canister detects the pressure of the fuel entering the tank and the computer opens the vent solonoid.

[quietkilla6]

you know i started this post and everyone just answerd that guys underfill problem? so im guessing you guys cant help me?

[R350Zz33]

go to dealer see what they say bro

[simplewon]

What do you mean by Bypass? Is this a simple fix or something? Please let me know more!

Power the the canister solenoid and the vapor solenoid with a switch under the dash, wire them with a large diode(allows flow of electrons in one direction) from radio shack so the computer doesn't detect a short during self test at start up.

Turn the switch on with the engine running to allow both solenoids to energize providing vacuum to the fuel tank from the engine.

The charcoal canister is supposed to detect slight changes in pressure that occur while fueling and open a vent solenoid to allow the tank to vent and be fueled. The system does not work well.

I bypassed the canister completely with the vacuum hoses on it, then switch the vapor solenoid on for added fuel vapor to the engine. I also installed a vented cap.

The z has to be running while fueling for this to work. Some states or stations won't allow fueling a running car. No one minds around here.