Fuel Gauge

[sipow]

When i brought this car i new it had a possible faulty fuel gauge DG couldnt find any probs with the sender and had tried to get hold of anew gauge(yellow) but couldnt get hold of one and told me if it played up to get back in contact ,which i havent yet.
The thing is that it works with the ignition on but as soon as start the engine it shows empty,anyone know of any tests i can do with multimeter to test the gauge without having the dash out?

Simon

[cammers]

I'd say it will be a bit tricky tryng to diagnose the problem without getting to the back of the gauge.
You could try grounding the sender, this will eliminate the sender, sender connections and the wiring between the sender and gauge!
Without removing the gauge, thats about all I can think of.
Sounds like a bad connection somewhere to me. Best way to eliminate the gauge would be to get at the back of it, ground one side, and make sure that you are maintaining voltage on the other side!

Mark

[GreenV8S]

quote:When i brought this car i new it had a possible faulty fuel gauge DG couldnt find any probs with the sender and had tried to get hold of anew gauge(yellow) but couldnt get hold of one and told me if it played up to get back in contact ,which i havent yet.
The thing is that it works with the ignition on but as soon as start the engine it shows empty,anyone know of any tests i can do with multimeter to test the gauge without having the dash out?

Simon

This rings a distant bell.

I remember a report a couple of years ago from somebody trying to find a problem with the fuel gauge. Turned out to be a failed relay, in the circuit from the sender to the gauge. Apparently switched by the imobiliser to enable the fuel gauge. Seems pointless to me but the best guess at the time was it makes the fuel tank look empty when the imobiliser is armed, so even if you hotwire the starter circuit it won't start and will look like its out of fuel. Sounds crazy I know. I seem to remember the relay was reported as being behind the dash where you can't quite get to it from either side. May be worth searching the archives to see if you can find the posts about this?

Cheers,
Peter Humphries (and a green V8S)

[sipow]

Cheers Mark and Pete,

I'll check out the archieves for any info,Does sound a bit wierd and crazy,Hey but thats TVR's and it dont suprise me that the relay that could be faulty is behind the dash:headbang:

Simon

[JFF]

I can confirm that there is a wire from the fuel gauge to a relay which then connects to part of the original TVR alarm system. As when I collected my 1992 4.0Lt Griffith from having it's alarm system changed to a Clifford system the fuel gauge no longer worked. After testing the sender and the gauge which where fine, it was discovered that a wire runs from the gauge to a relay block that was tucked down below the stero inside the dashboard. This relay then had wires running down to part of the original alarm under the centre consul. The alram installers had removed the old alarm and cut the earth feed wire to the relay. As soon as this connection was restored the fuel gauge functioned fine again. This took a whole day to trace this problem, with lots of trim panels and carpeting and the dashboard panel being removed.
The easy way to check if it's the sender at fault is to join the two wires on the sender unit together with the ignition on. If the fuel gauge then registers full then the sender is at fault. The fuel sender on my Griffith was located on the N/S edge of the fuel tank. I beleive later cars had the sender on top of the fuel tank. The other test you could do is to remove the dasboard and then run two new cables from the fuel gauge externaly round the car and onto the fuel sender and turn the ignition on and see if the gauge then works. If it does then it means the problem is somewhere in the wiring between the gauge and the sender.
I hope this helps.

Justin