Fuel gauge working erratically

[MD355]

Since I bought the my 2001 Lotus Esprit V8 the fuel gauge has been working erratically. When I fill up the car it is slow to show the full reading.. And after the last service the fuel gauge seeks to go crazy.. It will show zero and minutes later it will show half full.. Any solution ?

[Escape]

Sounds like an electrical problem, maybe a connector working lose.

[AndyPG]

Hi Makis,

I know on earlier cars, including my SE, if I fill up the left tank, it will take a few minutes until the level equalizes with, and rises in the right tank where the level sender unit lives.

Also, the fuel gauge has no damping electronics on it so it does show a very changeable reading as you drive along and the fuel is sloshing around.

These things are quite normal on early cars.

Maybe on later cars, like yours, this isn't supposed to happen.

Does the gauge erratically jump around while the car is stationary?

Andy.

[MD355]

Hi Andy and thanks for your reply !!

Before the service, as you mentioned the fuel gauge was just slow to adapt to new fuel levels.

During service we had to remove the dashboard and after service now the gauge is behaving strangely. Even stationary, the gauge jumps around

I will take it back to remove the dashboard and see if a connector is loose

[LotuStuart]

I do not trust my gauge at all, but the LOW FUEL light works.

Sparky advised me to ignore the gauge but take notice of the light, and that has served me well.

If i put 40 litres in, and reset the trip, i know roughly how long i can drive for. About 180 miles is safe.

YMMV

[AndyPG]

2 hours ago, MD355 said:

During service we had to remove the dashboard and after service now the gauge is behaving strangely. Even stationary, the gauge jumps around

I will take it back to remove the dashboard and see if a connector is loose

Ah yes. Could easily be a dodgy connection. Check that any binnacle common ground wire connections have been refitted securely too.

Andy.

[MD355]

Update : I went to my mechanic and he checked the cables behind. He said the cables were ok and most likely it was a problem with the fuel gauge. He played around with the cables a bit, and the gauge sort of started working. 

After a road trip the gauge is now showing completely zero.

If I knock it with my finger a bit, the needle will move and show something, but this will go back to zero soon.

Could it be the fuel gauge that is faulty ? Thanks !!

[ramjet]

I would be checking the cables again and don't just check the earths, but remake them.

I have been surprised how many confusing electrical issues on these cars can be fixed by just undoing, cleaning and remaking the earths.

[LotuStuart]

On 14/03/2020 at 02:02, ramjet said:

I would be checking the cables again and don't just check the earths, but remake them.

I have been surprised how many confusing electrical issues on these cars can be fixed by just undoing, cleaning and remaking the earths.

I always say, if you have an electrical problem, its the earth. 
And if it isn't the earth, then it's a problem that happened because of the earth.

In a plastic car, it's worse

 

[MD355]

I tried everything.. I think its time to replace the gauge for my 2001 Lotus Esprit V8 USA spec. Anyone know where I can find this part ? I contacted Steve from a well known company in the UK that specializes in Lotus and he said it has been discontinued.. 

He will try to find it.. Just in case he doesn't find it, this is the part number.. Any suggestions ?

05b        Fuel Gauge, unleaded graphic VDO, calibrated for smaller tanks USA ‘00 MY on, non USA ‘01                  A082L4336F

Thanks !!

[fjmuurling]

Have you checked the sender unit in the tank?

If it is similar to the one in an SE it is easy to check. Disconnect the the plug on top of the tank and use a potentiometer (variable resistor) connected to the connector. Observe the gauge as you turn the potentiometer (vary the resistance). If the gauge works it is the sender at fault.

 Use a potentiometer in the 200 Ohm range (I might be wrong) (a standard value is 270 Ohms).

[MD355]

5 hours ago, fjmuurling said:

Have you checked the sender unit in the tank?

If it is similar to the one in an SE it is easy to check. Disconnect the the plug on top of the tank and use a potentiometer (variable resistor) connected to the connector. Observe the gauge as you turn the potentiometer (vary the resistance). If the gauge works it is the sender at fault.

 Use a potentiometer in the 200 Ohm range (I might be wrong) (a standard value is 270 Ohms).

I actually installed a new sender unit... and the results were the same...

I ended up putting back the old sender unit..

When I knock with my finder on the fuel gauge sometimes it will work... so my guess is that it is probably the magnetic coil inside that is faulty...

Let's hope changing the gauge fixes my problem...

[MD355]

Update : 

So today I decided to replace the Fuel Gauge by myself !!!

I followed some online instruction and managed to remove the cover and instrument panel...

I unscrewed the faulty gauge and installed the new one..

Immediately it worked !!!

I was so proud of myself !!

I called my mechanic and he was proud too... He asked how long it took me... almost 3 hours.. and we jokingly agreed that he is underpaid when he does the serious staff on my car, like engine rebuild..

Last thing, I reinstalled the leather cover of the instrument panel, but I cannot insert the two allen screws... what is the trick ?

do the supports that lock the allen screws need to be on the leather cover or the instrument panel ??

I left them on the instrument panel... maybe thats my fault ?

Thanks !!