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Discussion Starter #1
Do you know what the specs are/how to test the fuel level sensor. My fuel gauge started reading E no matter what the fuel level. The guage was not accurate beforehand either, usually read empty after 10 gallons or so.
The low fuel light would usually come on with about 4 gallons left, but has since stopped working. (that may have something to do with the autolumination LED bulbs I installed recently, but did NOT change the low fuel bulb.)
I have pulled the cargo tray off and opened up the tank, the right side port contains what I figure to be the fuel level sensor, as it has a boom that raises with fuel level. Is there a way to ohm test it. Looks like a potentiometer of sorts.

Thanks in advance!
 

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Well there are ways to test...

the float gauge....
Disconnect the harness and face the harness leading to the gauge unit towards you with the locking tab on top. Grab a voltmeter and set it to OHMS
place the positive probe on the terminal that is directly under the locking tab on the harness and the negative probe on the remaining terminal. Now with the float at the bottom side (empty) the OHM reading should be 78.3 OHMS to around 84.8 OHMS. With the float positioned in the center the reading should be 27.7-34.3 OHMS and with the float positioned at the top of the scale (Full tank) the readings should be 4.3-5.8 OHMS.
MaxDoc
 

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Discussion Starter #3
your knowledge astounds me sir! thank you so much. I will test that, hopefully without blowing myself up, and report back any findings!
 

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Discussion Starter #5
alright, here's what I got.

I removed the assembly from the tank. The locking connector going to the sensor has two pins side by side, underneathe the locking mechanism, but neither pin was directly below it. I don't think it really matters too much. A yellow wire goes to one pin, and a black wire to the other.

This is with the multimeter set at 200 ohm range. With the boom in the empty position (all of the way lowered), I get a reading of 163.8 ohms. In the full position, it reads 10.3 ohms. Everything else ranges in between those numbers. I also reversed the probe pins just to make sure, but as expected the was no difference. I would suspect this is a problem since these numbers are nearly double at the empty side, and at the full side.

on a side note, does the low fuel light work off of this same sensor or a separate one?



Post Edited (Jan 20, 3:33pm)
 

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By the way before your gauge was accurate. All Z32 guages read E after about 10 gallons has been used and when the gas light comes on it generally means youve got about 4 gallons or so left. I hardly ever got more then 13 gallons of gas in my tank.
 

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Discussion Starter #7
how does the low fuel light work? is it activated when the float gets to the bottom, or is there another float that operates it. The only reason I ask it that the guage went dead, but the low fuel light still worked for 6 months or so. Then the light quit working. Since the light slowly fades on as the gas gets lower, I didn't know if the same potentiometer was operating both the gauge and the low fuel light.
 

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Discussion Starter #8
okay wait a minute. during my research, everything I read says that the fuel level sensor is on the left side of the tank next to the fuel pump. what I'm messing with is on the right side and has a fuel hose running over to the left side. I saw a separate connector that somewhat describes what you were talking about on the left side. What is the sensor I seem to be messing with?!!! I don't wanna go to the junk yard to get the wrong part!
 

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Mr. Haulnazz15...........

Looks like I owe you an apology.......The info on the OHM readings I gave you this afternoon were for a 2+2 (I had a major brain fart this afternoon ) ... After reading your post just now I could not beleive the OHMs could be that far off so I rechecked the stats in my FSM.

It appears since you have a coupe your readings are within spec. On a 2 seat coupe the full OHM reading should be between 8.6-11.6 so your 10.3 is good. On the empty readings the range is 157.6-170.6 your reading was 163.8 so that is good as well. Now on the coupe there should be a main tank and sub tank harness. The Yellow and black leads run to the sub tank float. You need to locate the orange and black leads for the main tank float and test those as well. The OHM readings are the same for both. The orange lead is the lead that runs to the dash gauge unit.

You can check the gauge opperation by removing the gauge cluster but leaving the harnesses connected On the back of the cluster on the side of the cluster where the fuel gauge resides you see 3 brass machine screws. One is marked + one marked - and one marked F. Turn the ignition on but do not start the car. Ground a jumper wire to a spot on the car and touch the other end to the machine screw marked - (negative). The gauge should move smoothly to the full mark.

The low fuel sender looks like a small pop can with a single lead sprouting from the top. I am not an electronics expert so I cannot tell you how the little bugger works. That I will defer to Mr. JT240Z as he seems to have a far greater electrical background than I do.

I again apologize for the bad info.

MaxDoc
 

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Discussion Starter #10
lol, no prob Doc, you still gave me the info I needed, and its been like this for quite a while so time was not of the essence. I wasn't aware that it had two separate sensors. I will check the other one tomorrow. Thanks again for posting the additional info, I'll check the bulb and gauge tomorrow too.
 

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The right side unit is the ...

sub tank unit. The left side has the main gauge unit and both have floats. I guess the reason is the tank has an indentation in the bottom much like a drive shaft tunnel.
The fuel pump / gauge unit should have the orange lead and black lead to it.
MaxDoc
 

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Discussion Starter #12
k, pulled the left side main tank unit, and guess what I found?!! The boom had somehow gotten locked beneathe the lower tab on the potentiometer. So thats why it was reading E. (good thing it didn't originally get trapped on Full when it happened!) Anyhow, ohmed it out anyway, checked out almost the same as the subtank unit, put it all back together, and we now have a working fuel gauge! Thanks MaxDoc (and Cville) for your help!

. . .a problemless Z32. . .how long do you figure it will last? lol knock on wood
 
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