Fuel gauge fault diagnosis help please
Discussion
As a few of you know I have bought a 94 Chim 400 and I am thoroughly enjoying it (don't let the Griff owners know)...
One of the jobs i need to sort on the car is an erratic fuel gauge reading. The fuel gauge when full reads full no problem but after you have done about 40-50 miles it starts bouncing between empty and full. The more miles you do (so th elower the tank) the more the needle bounces from full to empty to full to empty...and so on.
My first though is the sender as the gauge does have cull and free movement so maybe the sender unit is sending some odd signals as the fuel level moves off full.
With the needle either showing empty or full would I be right in thinking a bad earth or the sensor wire shorting out to earth could be the problem?
I have fixed many things on my various TVRs over the years but I haven't yet had to tackle a fuel sender so I wasn't 100% sure how they are wired. My car is a 94 with the black edges dials and the fuel gauge has a low fuel light in it (although I haven't let the tank run down to know if that works either).
One of the jobs i need to sort on the car is an erratic fuel gauge reading. The fuel gauge when full reads full no problem but after you have done about 40-50 miles it starts bouncing between empty and full. The more miles you do (so th elower the tank) the more the needle bounces from full to empty to full to empty...and so on.
My first though is the sender as the gauge does have cull and free movement so maybe the sender unit is sending some odd signals as the fuel level moves off full.
With the needle either showing empty or full would I be right in thinking a bad earth or the sensor wire shorting out to earth could be the problem?
I have fixed many things on my various TVRs over the years but I haven't yet had to tackle a fuel sender so I wasn't 100% sure how they are wired. My car is a 94 with the black edges dials and the fuel gauge has a low fuel light in it (although I haven't let the tank run down to know if that works either).
OK, some more info. I think the gauge is at fault.
I measured the resistance on the sender (multimeter set to 200 ohms and across the green black and black wire) and it returned 5.3. I went for a spirited 40ish mile drive and measured it again once I got home and I now have 8.1. So I think that indicated the sender is working correctly and the gauge itself is at fault as that is still pegged to full and as you drive jumps about from empty to full every few seconds.
So I will get a new gauge and swap mine over to see if that works.
I measured the resistance on the sender (multimeter set to 200 ohms and across the green black and black wire) and it returned 5.3. I went for a spirited 40ish mile drive and measured it again once I got home and I now have 8.1. So I think that indicated the sender is working correctly and the gauge itself is at fault as that is still pegged to full and as you drive jumps about from empty to full every few seconds.
So I will get a new gauge and swap mine over to see if that works.
I did post this...and I know my TVR's, I did speak to the guy that was suggested but I have not progressed on this.
I have been busy putting an externally battery on my speedo!
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Adrian@
I have been busy putting an externally battery on my speedo!
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Adrian@
Edited by Adrian@ on Thursday 11th September 21:22
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