Author Topic: Fuel gauge/voltage stabiliser  (Read 869 times)

Offline Dave

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Fuel gauge/voltage stabiliser
« on: 05 July 2012, 09:57:23 am »
My fuel gauge drops to about half after just 50-70 miles. After that it gently drops but then goes to almost zero after less than 150 miles. The engine is a Tdi and I know it does around 35mpg so there's nothing wrong there but I ran out of fuel on Monday evening and needed a BYT to get some more, which was most inconvenient.

I want to know why my fuel gauge is so shit.  :confused:

Does that voltage stabiliser thing affect the fuel gauge as well as the temp. gauge?

Are the gauge and the sender meant to be a matched pair?


Offline seriesewan

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Re: Fuel gauge/voltage stabiliser
« Reply #1 on: 05 July 2012, 12:00:14 pm »
Not sure about gauge & sender but  the stabiliser effects both gauges... i replaced my temp sender & the fuel gauge no longer reads to maximum  & both gagues read pretty low...

i pulled the dash to bits & did an experiment unplugging various senders etc from the system & removing either of the circuits caused the voltage on the other to rise suggesting that the stabliiser is not giving me enough juice to pull both needles to their high values

i have however not replaced said stabiliser yet but it sounds like you have a similar problem....   is the temp sender  the same on the tdi & series engine? it could be a different resistance range so therefor sapping the power from your fuel circuit.... try unplugging the temp sender temporarily & see what happens to the fuel needle
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Offline inglishg

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Re: Fuel gauge/voltage stabiliser
« Reply #2 on: 05 July 2012, 01:12:56 pm »
Both fuel gauges flick immediately to full when I turn on the ignition.

The volts at the changeover switch are around 6v, so I wonder if my volt stabiliser is at fault.

I'm keen to know a fix, coz it's a pain lifting the seat and peering in the tank to check if I can make a journey or not!
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Offline NoelC

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Re: Fuel gauge/voltage stabiliser
« Reply #3 on: 05 July 2012, 07:29:44 pm »
Both fuel gauges flick immediately to full when I turn on the ignition.

The volts at the changeover switch are around 6v, so I wonder if my volt stabiliser is at fault.

I'm keen to know a fix, coz it's a pain lifting the seat and peering in the tank to check if I can make a journey or not!

If you have a '65 motor then there isn't an instrument voltage regulator as far as I'm aware, the instant reading gauges (with the little arrows on the end of the needles) didn't have one. This came in from '67 onwards (suffix D black dash neg earth) with the slow reading gauges when the water temp gauge became standard, replacing the ammeter. The only exception to this is military clusters (the type with both oil and water temp) as these are either capillary or electrical designed to work with full voltage.
'55 107 truck cab ✪ '66 109 hardtop ✪ '66 109 LHD ex-MOD ambulance ✪ '71 109 one ton ✪ '72 88 2.5 petrol ✪ '72 2B FC Dorothy Perkins 4.236 ✪ '79 Lightweight LHD ✪ '79 109 LHD ✪ '83 109 FFR ✪'93 Disco Tdi ✪'94 Range Rover Vogue Tdi

Offline Billggski

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Re: Fuel gauge/voltage stabiliser
« Reply #4 on: 05 July 2012, 08:39:28 pm »
The rod on the sender unit in the tank could be bent, POs often adjust the rod so that the float moves up and down freely, but it is often a case of getting to know your gauges and what they actually mean.
My temperature gauge reads cold when normal and in the middle when overheating, the fuel gauge has a mind of it's own bur I fill up below halfway to be sure. Never put more than 35 liters in so it could be close, but I still keep a gallon in he back just in case.

Offline inglishg

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Re: Fuel gauge/voltage stabiliser
« Reply #5 on: 06 July 2012, 01:39:07 pm »
If you have a '65 motor then there isn't an instrument voltage regulator as far as I'm aware, the instant reading gauges (with the little arrows on the end of the needles) didn't have one. This came in from '67 onwards (suffix D black dash neg earth) with the slow reading gauges when the water temp gauge became standard, replacing the ammeter. The only exception to this is military clusters (the type with both oil and water temp) as these are either capillary or electrical designed to work with full voltage.

Interesting!

So, based on that, there SHOULD be a full 12v at the changeover switch???

It's such a pain having to keep tabs on mileage and physical checks on the level in the tanks.
1965 S2a 2.25P "The Shed"
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Offline Hairyvike

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Re: Fuel gauge/voltage stabiliser
« Reply #6 on: 06 July 2012, 02:50:24 pm »
...anyone who does a suspect voltage regulator can get a new one from Paddocks for just 5.75+vat.... http://www.paddockspares.com/148876-voltage-regulator-s3-behind-dash.html
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Offline Vinny

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Re: Fuel gauge/voltage stabiliser
« Reply #7 on: 06 July 2012, 09:04:01 pm »
^^^^^^^^

I did that and got no reading at all, so just put the old one on and just look in the fuel tank.
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Offline Time Bandit

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Re: Fuel gauge/voltage stabiliser
« Reply #8 on: 07 July 2012, 01:15:10 am »
There must be something about Land Rovers and fucked fuel gauges...? The fuel gauge in my Lightweight is also shite and don't work.
I couldn't swear on it but in my case I'm fairy certain it's the gauge itself that's paggered as it always just reads full as soon as the ignition is switched on, it does the same on both tanks. I don't have a voltage wotsit fitted so that being knacked is kinda ruled out I figured in my case. My electrical 'skills' are on the border between non existant and totally fucking useless so doing tests and stuff on the gauge and electrical side of things with multi meters and such like was a non starter but I did wire a bulb to the wire that came of the back of the gauge and to an earth and if you played around with the float on the sender you could get the bulb to go from off and right thru' to fully lit up depending on where the float was so it's obviously sending the correct 'electrickery' to the gauge and it seems the gauge just ain't doing its stuff....hence to my simple mind the gauge is fucked and after 13 years I'm used to it and ain't ran out of juice yet so it can stay fucked!!

Offline NoelC

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Re: Fuel gauge/voltage stabiliser
« Reply #9 on: 07 July 2012, 06:08:03 am »
Interesting!

So, based on that, there SHOULD be a full 12v at the changeover switch???

It's such a pain having to keep tabs on mileage and physical checks on the level in the tanks.

As far as I know, yes. Conveniently I'm in the US with the ambulance (a '66 with changeover switch) at the moment so I'll stick a meter on it to double check. Poor spades, dirty connections etc don't help. Last week's trip from Montana to Idaho had one tank reading full all the time, wierdly that was a dirty/poor connection to the sender. I'd always assumed that would give an empty reading but seemingly not.
'55 107 truck cab ✪ '66 109 hardtop ✪ '66 109 LHD ex-MOD ambulance ✪ '71 109 one ton ✪ '72 88 2.5 petrol ✪ '72 2B FC Dorothy Perkins 4.236 ✪ '79 Lightweight LHD ✪ '79 109 LHD ✪ '83 109 FFR ✪'93 Disco Tdi ✪'94 Range Rover Vogue Tdi

Offline feelinperky

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Re: Fuel gauge/voltage stabiliser
« Reply #10 on: 07 July 2012, 07:55:08 am »
Well my fuel gauge also reads off because i changed the float assembly. Also the earth for the sender earths through the tank to the chassis and i had hammered the tank on a rock and so was nt earthing to the chassis even though its connected. Worth putting a proper earth from the sender to the chassis. Also you can put resistors across the back of the gauge to get the right reading. Oh and mine does not have a voltage stabiliser as its too early.  ;D
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Offline Bert the Bodger

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Re: Fuel gauge/voltage stabiliser
« Reply #11 on: 07 July 2012, 08:03:40 am »
Where a stabiliser (not regulator!) is fitted its job is supply a steady 10 volts to the gauge circuit.Fitting  a sender made of runny excrement will completely fuck the job.

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Offline Time Bandit

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Re: Fuel gauge/voltage stabiliser
« Reply #12 on: 07 July 2012, 10:51:44 am »
...My electrical 'skills' are on the border between non existant and totally fucking useless so doing tests and stuff on the gauge and electrical side of things with multi meters and such like was a non starter but I did wire a bulb to the wire that came of the back of the gauge and to an earth and if you played around with the float on the sender you could get the bulb to go from off and right thru' to fully lit up depending on where the float was so it's obviously sending the correct 'electrickery' to the gauge and it seems the gauge just ain't doing its stuff....

After reading that again in the cold (and more sober) light of day I've spotted my deliberate (ho hum) mistake...the bulb was wired between the power input to the gauge and the sender wire, not an earth, basically the bulb became the fuel gauge.

Offline Dave

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Re: Fuel gauge/voltage stabiliser
« Reply #13 on: 07 July 2012, 08:41:50 pm »
The rod on the sender unit in the tank could be bent,

I doubt it. Before I replaced the bulkhead and gauges it all worked fine. The thing is the temp gauge has a resistor inline to keep that one from constantly reading too high! So I've got a gauge that otherwise reads high and one that reads low.

I could do with a military tank then I could just take the cap off and have a look inside.

Offline NoelC

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Re: Fuel gauge/voltage stabiliser
« Reply #14 on: 10 July 2012, 05:18:20 pm »
I've checked the ambulance and that is showing 8 volts at the tanks. That surprised me somewhat, there must be a reg somewhere then.  ???
'55 107 truck cab ✪ '66 109 hardtop ✪ '66 109 LHD ex-MOD ambulance ✪ '71 109 one ton ✪ '72 88 2.5 petrol ✪ '72 2B FC Dorothy Perkins 4.236 ✪ '79 Lightweight LHD ✪ '79 109 LHD ✪ '83 109 FFR ✪'93 Disco Tdi ✪'94 Range Rover Vogue Tdi