Fuel Gauge Wiring and Connections

[nico506]

Hi aLL,
I have a fuel gauge with three spade connections to the rear and as I have a lan +2 speedo with fuel warning light, and althoughI fitted the gauge initially thefuel tank reading was 3/4 full wich was correct, however since then it now reads full all the time.

At the moment the wiring is connected as follows: (taking the positions looking at the gauge from left to right

Spade connction 1 - Green wire to Voltage Stabliser which is new.

Spade Connection 2- wire to fuel warning bulb and then fom Bulb to earth

Spade connection 3- Green/Black wire to fuel sender unit on tank

The gauge has been refurbished and tested by Susan Miller aka Mick Miller Classics.

My question is is this correct or should connections 1 and 2 be swopped over?, I have an alloy tank and ask if the earthing is having an effect on this reading in any way. The sender unit is also new.
Any comments or experience on this helpful as it is disconcerting at times, and have looked in the Archive- but wiring diagrams or info not clear as to which way the gauge is wired up.
thanks for help in advance
Nico
LotusElan 1968 S3 DHC

[bob_rich]

Hi

According to my circuit diagram ( which is for a +2 after chassis 72050732L) green/black should be the lead form the sender to the fuel gauge. black/brown should be the lead for the warning light in the tacho and black should be the ground end of the sender which should be earth. I would suspect and earth problem the low end of the ender to earth being the risk.

I have my tank out while rebuilding and checked the resistance of the sender and info is in the note attached.

It might also be important to check the body of the gauge is grounded OK

If you have or can get the use of test meter you could check the the sender has a resistance to ground to see if the sender is OK.

best of luck

Bob

[bob_rich]

Apologies all!!

I made a mistake using my DVM and the reading for the full tank should be around 35 ohms not 860 ohms as I put in the note. Should have spotted it as to move the gauge over towards full more current would be needed so lower resistance required. Sorry 4 that cock-up. Updated note attached

bob