Quote:
Originally Posted by Brian
And I have a question too - sorry!
Running 36 fuel tank, original sender, original dash unit, 12 volt conversion, [alternator], runtz on gas gauge, another on oil pressure gauge.
Problem is that upon turning on ignition, needle in fuel gauge will climb and indicate [approximate] fuel level, but then when I start the engine and start driving, the needle goes down below empty and stays there.
Why would this be?
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I know I'm resurrecting a 3 year old post here, but I'm wondering if Brian ever sorted out his fuel gauge problem where it would start reading ok then dropping back to zero - because I'm having somewhat of a similar problem, but I'm pretty sure I know what's causing mine.
I found the points in the sender unit pitted and dirty, so I disassembled the thing, - yeah, you can disassemble the things if you're careful ! -and filed the points flat to get rid of the pitting, (used wifey's nail file
) got them all clean, sprayed them with electrical contact cleaner, reassembled it, adjusted the little toothed adjusting wheel to get a reasonably accurate reading at the gauge and put it back in the tank.
All was good for half an hour then the needle decided to start wandering before dropping down to empty.
So I pulled the sender back out, cleaned and sprayed the points again, reinstalled it and same thing, except this time it lasted a little longer.
So I've tried this 3 or 4 times now and it keeps happening. If I tap the top of the sender unit while it's in the tank it comes good - (shitty points!?)
I've dissembled the sender unit a couple of times now and I'm happy that everything else is good. Earths out ok. I've earthed the tank to the chassis so I'm not relying on the tank holding straps for my earth to to sender unit.
Somewhere in the dim dark past in the back of my mind I seem to remember something about points (well, ignition points anyway) might have been "coated" to help against pitting, or going resistive. Is that true? Perhaps I've taken that coating off by filing them ?
Wiring's all new and good. I rebuilt and rewired the car. And I'm using a single LM7806 IC heatsinked to the steel dash cluster to drop 12v down to 6v. They're not rated to draw 2 amps, (which is what I measured when the contacts were closed) but the IC's not getting hot, the oil and water gauges are reading ok and I'm measuring 6volts at the ign side of the gauge.
So there ya go folks. What the bloody hell's going on here? Your thoughts ?
Mick
(In real Tasmanian Devil country)