Fuel Gauge Problem

[Silver Shadow]

I went to test my car to a circuit after mountain chip installation. It goes unbelievably well however something happened to my fuel gauge. Now it always indicates full although it come to empty when I turn off the car. Does anyone knows what is wrong? I would appreciate any help. Thanks.

[Doug]

Same happened to me -- only way I could fix it was to replace float sender unit in the fuel tank.

[Silver Shadow]

Thanks for your reply. Now I have different problem. How do I can gain acces to the fuel tank? I know there was a wiki explaining this, but wiki is out for several days now. Can someone point me out at the right direction?

[Enright]

Yes, here you go:
http://www.lotuselancentral.com/manuals.htm

[Doug]

you get to the top apeture of the fuel tank by removing the plastic tray that is the floor of the convertible stowage area -- the battery is on the far right and the fuel tank is on the far left -- the fuel filter is also down there so something to plan to replace while there

mine did the same as your gauge and I remember learning the circuit and testing all the wire voltages, but it was the sender and there's nothing you can do short of replacing it

[Silver Shadow]

Is the sender unit unique from Lotus or is there any other that will work?

[Coupeboy]

I should imagine this is unique to the tank for calibration purposes; the sender also includes the fuel pump as a combined assembly. This would explain the price (£250 + seals). Having had an electric fuel pump (BMW) fail on me I could almost forgive the price knowing that I'm getting a new fuel pump as well. Alternatively You could always monitor your trip distance resetting every time you fill up? My experience of the Lotus fuel gauge is that it provides an idea of how much fuel you have but is a very rough reading and I check it against the trip distance anyway.

[BFG in the BRG]

Whilst I have never had the problem myself,
I thought a fuel guage always reading maximum could be caused by a faulty earth on the sender - or was it the positive wire was earthed.....
might be worth checking continuity before spending dosh....
or make a dipstick.
Mine only reads 3/4 when the tank is full - apparently it's because the sender is not perfectly alighed - there is a thread somewhere on this, and might save some frustration if you are replacing.

[Coupeboy]

My fuel gauge also reads 3/4 when the tank is full - would be great if the fix for this is straightforward and somebody's already done it?

[Paul.P]

When having to clean my tank out ( due to diesel contamination ), it took us 3 attempts to get the sender unit in the right position, due to the unusual shape of the tank. If i remember right, the 1st time once it was filled up, the gauge showed full all the time, 2nd time it went down to 3/4 & stayed there, 3rd time we got it right

[Coupeboy]

was the adjustment to achieve correct fuel indication a matter of slight rotation of the sender unit at the top of the tank and then relocking the lock ring? (I'm guessing a bit as to what you did being unfamilar with the design). Seeing as my car is currently SORN and I'm doing all sorts of fixes this could be one to add to the list!

[Paul.P]

was the adjustment to achieve correct fuel indication a matter of slight rotation of the sender unit at the top of the tank and then relocking the lock ring? (I'm guessing a bit as to what you did being unfamilar with the design). Seeing as my car is currently SORN and I'm doing all sorts of fixes this could be one to add to the list!

To be honest, my nephew did it ( who owned a garage at the time ), but i'm pretty sure thats what he did.

[Oscarthecat]

Whilst I have never had the problem myself,
I thought a fuel guage always reading maximum could be caused by a faulty earth on the sender - or was it the positive wire was earthed.....
might be worth checking continuity before spending dosh....
or make a dipstick.
Mine only reads 3/4 when the tank is full - apparently it's because the sender is not perfectly alighed - there is a thread somewhere on this, and might save some frustration if you are replacing.

You'll be pleased to know that (11 years on) it still does this. As long as I keep above a quarter tank I can live with the problem. Fantastic car BTW.

[Rambo]

But what if the car, when reading a quarter on the gauge, actually has an empty tank

Personally, I would set the trip when I filled up and allow ~250 miles before next full tank

[dapinky]

It all seems like a load of hassle when you can just carry a gallon in the boot.......

[Tanz]

Just adding to this old thread in case it is useful to someone. My gauge shows empty when it is half full. Pulled the gauge pump assembly out of the tank only to discover the that the float was 3/4 full of fuel. It doesn't show up well in the picture so have added an arrow to indicate the level. Have ordered a new one from here https://www.ebay.co.uk/itm/Smiths-New-F ... 2364099104