fuel gauge sender problem

Mr M

Junior Member

Posts: 10
#1

fuel gauge sender problem

01-21-2017, 02:54 PM

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........

Last edited by Mr M; 01-21-2017, 03:04 PM.
flatfoot

Senior Member

Posts: 253
#2

01-22-2017, 03:09 AM

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

Junior Member

Posts: 10
#3

01-22-2017, 02:35 PM

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
Sticky Sam

Junior Member

Posts: 2
#4

02-06-2017, 04:36 PM

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.
Z_Karma

Administrator

Posts: 3318
#5

02-06-2017, 05:00 PM

Originally posted by Sticky Sam View Post

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:

http://www.xenonzcar.com/z31/fsm.html

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

84 AE/Shiro #683/Shiro #820/84 Turbo
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#5.1

Sticky Sam commented

02-06-2017, 05:17 PM

Ta for the help and welcome. I do have the Haynes manual, as far as I can tell it has just one drawn picture of the sender but nothing about replacing it. I think I have downloaded the Zed manual, not so hot at this computer malarky. I will unscrew the second plate tomorrow and have a shuftie. I did jiggle the two wiring harnesses but nothing happened. Guess I will replace the sender unit. Nice Jam Jar by the way.

fuel gauge sender problem

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