Fuel gauge issue

[stag36587]

My fuel gauge stubbornly refuses to move so I searched through the forum for answers but couldn't find anything that quite describes my problem.

Fuel gauge shows empty despite tank having 10 litres of fuel, so I started to check wiring at the voltage stabiliser with my multimeter.

At the double green wires I get 11.8 volts. At the single green feed wire next to it I get a variety of readings between 0 and about 1 volt but normally hovering between 0.15 and 0.36 volts. I get similar output on other side of voltage stabiliser, i.e. the connection between it and the fuel gauge.

I checked fuel gauge by connecting it to a 9v battery and it works. Only other thing I haven't checked yet is the sender (which is new)

I tried shorting out both the sender to body and fuel gauge to body but got no output (maybe the earth I chose wasn't good enough)

I also got the same results using fuel gauge and stabiliser from a broken spare speedo.

Am I doing something obviously wrong (e.g. not enough fuel in the tank to register!) or do I need a new stabiliser perhaps?

Thanks

[GarethB]

I've got what appears to be the same problem.

I didn't check the voltage around the voltage regulator like you but I did check continuity between in the cable from sender to gauge and got nothing. Made a new cable and current flows but nothing on gauge once everything is connected up.

When the sender cable end is earthed to the tail light earth (which In know works because I had the lights on) and still nothing, but I do get a voltage of about 8 volts.

Can someone tell me if my gauge is connected properly; Green from voltage regulator to the E side of gauge and sender cable to the F side.

Will try your 9 volt battery method to test the gauge is working.

Hopefully someone can help both of us.

[bmcecosse]

Maybe stabiliser not connected correctly? I would by-pass it temporarily to see if that works the gauge. But your recorded volts are incredibly low. The stabiliser works by pulsing on/off to create an artificial effective 10 volts - you should see that on your meter with readings flicking up to 12 and down to 0.

[stag36587]

Yes all a bit strange Roy. I think stabiliser connections are all ok. Double green wire and single green wire connected to the 'B' terminals, then single short wire from 'I' connector to the fuel gauge.

I was a bit surprised that the single green wire only showed very low voltage before it joined the stabiliser, so I substituted that wire with a different one wired direct from the fuse box to the stabiliser but that made no difference either.

[bmcecosse]

Just bypass it completely for a test.

[GarethB]

Results I got following the tests mentioned above are:

1) Bypass stabiliser get full scale deflection on fuel gauge (empty to Full)
2) Double green wire to stabiliser get 12.5 volts (fluctuates a little)
3) Single green wire to stabiliser from main loom 6.5 volts.
4) Stabiliser to single green for fuel gauge was about 0.65 volts.

Next step order a new stabiliser and then see if there is a better way to earth the sender unit to see if this gets results.

To anyone help confirm my stabiliser is connected correctly, these observations are looking directly down to the speedometer unit when it is pulled forwards slightly. so fixing bolt is to my left.

Double green wires from main loom to first terminal of stabiliser
Single green wire from main loom to second terminal of stabiliser
Single green to fuel gauge left terminal to the fourth terminal of the stabiliser.

Thanks

[stag36587]

hi Gareth, late tonight I tried to bypass the stabiliser but got no movement at all so thinking I better investigate earthing at the tank end next. My stabiliser is wired exactly the same as yours.

[Trickydicky]

If you can't get hold of a replacement stabiliser, here is a link to make a solid state one
http://www.britishv8.org/articles/mgb-v ... ilizer.htm

[bmcecosse]

If by=passing it doesn't help, then that's not the fault. earthing the cable at the tank should give a FULL reading - give it time to get up there - if it's black, then it's a 'hot wire' gauge.

[stag36587]

In view of my intended trip to The National this weekend I have been looking at my fuel gauge issue again. I've done all checks as above and re-checked all connections and replaced voltage stabiliser with a newly manufactured one. Turning the ignition key, the needle moves from the extreme left to the first mark - taking 1.5 minutes to get there! From memory there is about 12-15 litres of fuel in the tank. Surely I would get a higher reading?! Only other thing I haven't done yet is to remove the sender (new) to check resistance.

This will be the car's first main trip (80 miles from home to the show) since its full rebuild - it's driven fine on short journeys so far but what other precautions should I take? I thought I would take water, oil, rotor arm, condenser, points, etc..... and the wife in the "support vehicle"

[bmcecosse]

Sounds about right then - carry a spare gallon. Have faith - you don't need a 'Service Wagon' following you - it's not the Monte Carlo Rally!!

[stag36587]

Sounds about right then - carry a spare gallon. Have faith - you don't need a 'Service Wagon' following you - it's not the Monte Carlo Rally!!

Ahem - wife now has taxi duties for the kids so support vehicle will be otherwise engaged so will just have to get on with it At least it should be good chance to try out my "replacement" speedo, cannibalised from two poor ones to hopefully make one good one.

[stag36587]

Well I almost got to catton hall in the Minor - went to fill up with fuel and it would only take £2.88 worth before the pump clicked off. Unfortunately fuel was by then leaking between the filler pipe and the bodywork I will investigate all that tomorrow. And the gauge is still only reading on the first "empty" mark.

[stag36587]

Had a spare moment to revisit this longstanding issue.

With a new voltage stabiliser I now (unlike before) get a very consistent 10 volts coming out of the stabiliser to the fuel gauge and from the gauge to fuel sender.

I added an extra terminal to one of the sender screws and connected the fuel gauge wire to it -the gauge now reads full. Connecting a wire direct from the this extra terminal to a known good earthing point in the body and the gauge reads empty. Adding an extra wire between tank and a good earth makes no difference either.

Checking the resistance with the sender still attached to the tank I get 26ohms which I think would be consistent with a relatively full tank (which it is).

What am I doing wrong to make this work or perhaps sender is faulty (even though new)?

Thanks for any advice

[bmcecosse]

Sender arm could be bent ?

[stag36587]

Possible I guess though it was a new sender - I'll remove from car to check anyway.

[bmcecosse]

Remove from car and move it up and down -does the gauge respond - remember it will be slow to move - it's a hot wire gauge.

[stag36587]

An inspired suggestion Roy. I've just removed it from the car, connected to the multimeter and got about 20ohms on full and about 195ohms on empty. And the fuel gauge now works.

So what was wrong?

The only thing I can think of is that the sender may have been catching somehow on a baffle inside the tank (I've shifted it round by one bolt) Otherwise the gauge is reading around 3/4 full although the tank looks fuller than that - but steady 10volts at the tank so maybe it's as accurate as it's going to get.

Do you like whisky Roy? You deserve a wee dram!

[bmcecosse]

Well done, glad it's working now - and cheers! -good to meet you today. Enjoy your holiday. Roy

[Nickol]

Now that you have it sorted, I can tell this tale without creating confusion.

The gauge on my '68 Traveller also only read half full but with so much fuel in the tank it was visible in the filler pipe. I played around with the voltage Regulator, the Feeds and had the Sender unit out to check. All seemed ok but still only reading half full.

Then by chance I was checking the spare parts supplier diagrammes - the Sender for my model looked very different and sure enough, someone in the past had fitted one for an earlier model probably with +itive earth.
Having purchased the correct Sender unit, all was well.