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Discussion Starter #1
Hello,

I have kind of half a question. I have a 1986 300Zx with an "analog" dash... What is the "lower" fuel gauge for? It ranges from an eighth to a quarter tank. My "upper" fuel gauge, what I would consider the real one, has a scale that reads down to "E." So maybe someone can tell me, cause I have never seen that lower gauge move, or any kind of needle there, or the main needle "reset" itself to intepret that lower scale. Althoug I will say that the Z seems to go from a half to empty too quickly.

Running on fumes, or full to the brim?

Thanks.

P.S. I don't have the original owner's manual, so I cannot consult that.
 

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the bottom one tells you how close to empty you realy are when you get lower then a quarter tank. Ive knoticed the same thing with the half tank dropping to empty real quick.
 

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Okay good questions I have experiance with this because I had to replace the gauge in the tank. Because mine wasn't working right.
The small gauge doesn't come out till you have driven the big gauge down past the E mark then the little red needle will show you exactly how much gas you have till empty when the red one comes out and it gets down to about 1/8 the fuel light should start coming on and off also... But thats all its for is to show you exactly how close you are to running out of gas
 

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If your Fuel Sending Unit is malfunctioning it can also effect the smaller guage.

The smaller guage is intended to show you how much gas you have from 1/4 tank down to completely empty. It is really helpful for guys like me who will ride it down to the last drop of gas before filling up.

When my FSU was malfunctioning my 1/4 tank guage seemed to work still because I would know it was time to fill up when that red needle dropped down. I cannot verify it's accuracy at that time though!

The new style of FSU's has two arms. I assume that one of the arms is for the quarter tank guage.

Hopefully that helps!
 

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Discussion Starter #5
Now the "just in case" question...

Thanks y'all,

Lots of great answers to explain that second gas gauge on my 86/300Zx with an analog gauge package.
Significantly more important, I JUST DISCOVERED I GET BETTER GAS MILEAGE! Now I just have to muster the courage to let the needle get buried further below "E" and hope that the big red one will drop. heh. At least now, I found a purpose for that one gallon gas can, besides the chain saw. Z's are two strokes, right?

Now the "just in case" question, how do you restart a Fuel Injected Z on the side of the road?

In the olden-Z days (twin SU's) it involved a funnel with a long hose, puddles of gas on the ground, cans of spray ether, a fresh starter, and a strong battery... If asked I can regail y'all with a hilarious story about my "good samaratan" deed gone horribly wrong... LOL and ended with a scorched favorite shirt...
 

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There is nothing special to restarting most petrol injected motors that have run out of fuel. In the case of the Z31, I would cycle the ignition switch a few times to run the fuel pump and circulate the fuel then crank away. The combination of manifold vacuum and 30+ psi fuel at the injector should take care of any bleeding necessary.
 
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