Fuel gauge

Post here for mechanical and engine topics such as fuel issues, transmission problems, rough idle, exhaust, electrical issues, etc

Moderators: GRNSHRK, ron, bfons

Post Reply
User avatar
Boggie
Posts: 185
Joined: Wed Jan 31, 2018 3:57 pm
Location: Buckinghamshire UK

Fuel gauge

Post by Boggie »

Hi all,

When empty my fuel gauge reads 1/3. I have removed the sender and tested resistance. 3.2 ohm on full and 73 ohm on empty. I can hear the float inside slide up and down anb in both cases it appears to hit the end stop. If I short the wires the gauge reads full, if I disconnect it reads empty so not sticking.

Any ideas please?
1985 M635CSI
Classic Car and Bike Collector & Restorer.
baders
Platinum Member
Platinum Member
Posts: 1084
Joined: Sun Nov 23, 2014 7:38 am
Location: Perth Australia

Re: Fuel gauge

Post by baders »

The values you tested appear OK for the sender unit. I made up a tester using a 100 ohm variable resistor to test back the other way to the cluster and gauge. See my post in the LOCUTUS build thread.
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement
User avatar
Soperman
Posts: 537
Joined: Tue Nov 25, 2014 2:44 pm
Location: London, UK

Re: Fuel gauge

Post by Soperman »

A finger of suspicion is pointing towards the circuitry behind the instrument cluster here, a common ailment on these cars.

Other symptoms often include erratic temperature gauges and haphazard service indicator lighting etc so if you have any other gauge or instrument issues directly behind the steering wheel you might want to investigate further; and you dig deep enough into this forum you will find a tonne of information on resolving such problems.

Good luck.
E24 M635CSi
User avatar
Boggie
Posts: 185
Joined: Wed Jan 31, 2018 3:57 pm
Location: Buckinghamshire UK

Re: Fuel gauge

Post by Boggie »

Thanks chaps!

I will add it to my list. I will have a dig aroung tge forum when I get a moment. Are the issues easy to see/resolve and could the rechargeable battery in the dash be affecting this?
1985 M635CSI
Classic Car and Bike Collector & Restorer.
Post Reply