Fuel Gauge fails when lights on

[browniecool]

Hi there, has anyone experienced a problem with the Fuel Gauge when the lights are turned on? The Gauge registers fine in the daylight but as soon as I turn the lights on it registers empty/doesn't register. I have been told it will be a bad earth - but where? Will it be the earth on the sender (unlikely because the sender is earthed through the screws into the tank) or on one of the lights?

I have also just started having problems with the oil light failing to register - will this be connected to the same problem?

Can anyone out there give me a clue?

Thanks,

John (browniecool)

[Orkney]

Scrape your fuse connection surfaces off first. Had a load of problems indicators & horn because of a corroded fuse connection so worth a look.
Could be a problem at the back of the speedo unit perhaps - maybe a short when the illumination light comes on?

[MoggyTech]

Faulty voltage regulator or dirty fuse box connections.

[Mogwai]

The speedo earths through the mounting screws on ether side if these are loose or dirty it can affect fuel guage & instument ilumination.

[browniecool]

Thanks Guys - all good tips and ones I will try ASAP. Will report back.

John (browniecool)

[Willie]

Also, do not assume that the sender is earthed via the tank to body screws. We have had experience on this forum of over zealousness with the painting causing the tank to be electrically isolated and rust could do the same thing. ( and no, the petrol pipe did not complete the earth connection)!

[bmcecosse]

It must be poor earth on the speedo - when no lights it can find a path through them, but when they are on the path is gone.