stupid fuel gauge

Post by **callyspoy** » Tue May 05, 2009 6:53 pm

right, some of you may have seen my new dash. if not there is a pic attached.
my problem is that the fuel gauge us blowing my fuses. it is a NOS item, so "should" be working fine.
when i reconnect the original fuel gauge, it works fine, and when i connect a later type one (that runs of a voltage reg) it goes up to full like it should as i don't have a voltage reg.
so any ideas? iw as wondering if the fact it is i think designed for pos earth might affect it? bit of a longshot but only thing i could of!
any help would be HUGELY appreciated!<br>

<br>

Post by **d_harris** » Tue May 05, 2009 7:12 pm

fit a later one and a regulator

Post by **callyspoy** » Tue May 05, 2009 7:14 pm

lovely idea Mr Harris, not what i want to do though. the gauge fits beautifully and took an age to make a suitable hole!

Post by **d_harris** » Tue May 05, 2009 7:39 pm

pffftttt...... excuses

Post by **callyspoy** » Tue May 05, 2009 7:45 pm

pah! that wasn't help anyway, that was another option! damn other options!

Post by **Mogwai** » Tue May 05, 2009 8:51 pm

what did/would the gauge originally come from? unlikely but could be pos earth I had a clock like that once the polarity was written on the face

Post by **mike.perry** » Tue May 05, 2009 9:02 pm

My original gauge in the Series MM only reads full or empty. I assume there is a problem with the sender unit in the tank but I haven't got around to taking the boot apart to check it. I just carry a can of spare petrol, dip the tank before I leave home to make sure I have enough petrol to reach the filling station and fill up at the start of a journey.

Post by **callyspoy** » Tue May 05, 2009 10:57 pm

agreed...on by ebay it is this type...on other ones it says it is A40, so is old me thinks. seems to be period with mine, as it is literally a black version of it, just with mounting lugs in a different place...

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0009452166

Post by **callyspoy** » Tue May 05, 2009 11:50 pm

found this on ebay, this is it exactly...
http://cgi.ebay.co.uk/AUSTIN-A40-MK1_W0 ... 1|294%3A50
should be positive earth surely?

Post by **bmcecosse** » Wed May 06, 2009 8:38 am

If you reverse the connections - what does it read ?

Post by **callyspoy** » Wed May 06, 2009 5:14 pm

nowt...

Post by **bmcecosse** » Wed May 06, 2009 5:57 pm

No fuse blowing ??

Post by **callyspoy** » Wed May 06, 2009 8:52 pm

oh yes, plenty of fuse blowing...it says so oop top.

Post by **bmcecosse** » Wed May 06, 2009 9:42 pm

Yes -but still does that with reverse connection was the question ??? If so - then 'polarity' is not the problem - it's just not suited to the fuel measurement system in the tank.

Post by **callyspoy** » Wed May 06, 2009 11:19 pm

oh okay,sorry! no it didn't blow when i swapped the wires over...so it *could* be polarity then?

Post by **PSL184** » Wed May 06, 2009 11:25 pm

Yes, it could well be - does the gauge earth out on the dash or mounting bracket? If so, it might be worth trying to isolate it so that you are just using the wiring terminals. Thought process - If intended for positive earth and you are connecting it negative earth and it is earthing though the case then your positively charged case will be shorting out to earth.... If you get what I mean?

Post by **bmcecosse** » Wed May 06, 2009 11:36 pm

I agree - sounds like earthing problem within the gauge. Reverse the car's polarity!

Post by **callyspoy** » Wed May 06, 2009 11:37 pm

i get exactly what you mean. it is bolted to the dash so is earthed out yes. i can't isolate it as i rivetted it in place on the dash mount, long story!
so do we think perhaps remove it from the dash, damn rivets, and try to isolate it? do the feed wires just go on as normal in this case? if this is the problem, is it possible to reverse the polarity of the gauge seperately? i don't much liek the idea of isolating the gauge, scary idea...

Post by **bmcecosse** » Wed May 06, 2009 11:39 pm

Not really practical to isolate the gauge safely. Don't see why it should earth through the case - but it does seem that way. Put a meter on it - from each terminal to the case - to see what rsistance you get at each terminal.

Post by **PSL184** » Wed May 06, 2009 11:41 pm

If you can get inside the gauge then it is possible to rewire internally but by far the easiest would be to fix it in place with plastic pop rivets and make sure the case doesn't touch the dash....