Forums/Z31P/z31-repairs-forums electronics/fuel gauge sender problem

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Mr M: (2017-01-21 19:54:47)

my fuel gauge has not worked since i got the car,i have unplugged the fuel sender unit in the trunk and measured the volts at the plug with the ignition on,its about 7.7 volts,ive changed all the relays in the footwell and in the relay box under the hood,and the two metal boxes by the spare tyre well in the back have nothing to do with it,does anybody know where the relay is that deals with the fuel gauge sender unit? i cant see anything in the book saying about it,mines a uk car but looking in the manual a lot of stuff is similar just on the other side on us cars........

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flatfoot: (2017-01-22 08:09:24)

Here in the US there's a 10A fuse that supplies switched power to the gauges. Middle Column, 3rd one down. From there the sender works as variable resistor to ground.

Basically your gauge is dropping the 7V.

Its my guess that you are not using a high impedance volt meter and its acting like the sender by providing a path to ground.

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Mr M: (2017-01-22 19:35:26)

yes you must be right,i tried a secondhand sender today wired up to the cars sender wires out of the tank with the float about half way(dry),and saw the gauge rise so its obviously a duff sender unit problem

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Sticky Sam: (2017-02-06 21:36:53)

First time on this site chaps, so don`t give me flak if I ask something obvious to some. My Zed ( 1986 ) also has duff fuel gauges. Like this chap I guess it is the sender unit. I looked under the rear carpet and found two lots of wire/cables going down through the floor. There is a circular plate with two screws, having taken the plate off I see a smaller circular unit with 6 or maybe 8 ( sorry I have forgotten ) screws/bolts. Would the sender be under or even attached to the smaller plate? Thank you in advance.

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Z_Karma: (2017-02-06 22:00:32)

{{#if:Sticky Sam|Sticky Sam wrote:|Quote:}}

First time on this site chaps, so don`t give me flak if I ask something obvious to some. My Zed ( 1986 ) also has duff fuel gauges. Like this chap I guess it is the sender unit. I looked under the rear carpet and found two lots of wire/cables going down through the floor. There is a circular plate with two screws, having taken the plate off I see a smaller circular unit with 6 or maybe 8 ( sorry I have forgotten ) screws/bolts. Would the sender be under or even attached to the smaller plate? Thank you in advance.

Firstly…Welcome to the site.

Secondly, if you haven't already, get the factory service manual:

https://dev.z31library.com/xenonzcar_archive/z31/fsm.html

Thirdly, yeah that's your sender unit under that plate.