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Help in checking gauges


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Hi all you wiggly wire knowledgable people, Getting there with business of staring up my 72 6 after 2 year rebuild from many boxes of bits, including 2 halves of a tatty body,(abandoned project) but I'm having difficulty establishing whether my Fuel gauge and Ammeter are working or not. <_<

 

Firstly the only register on the fuel gauge is a slow creep up to the empty mark even though I've put at least 3/4 gallons of fuel in the tank. I have fitted a Revingtons alloy tank with a new standard fuel sensor. I'm wondering if the shape of the Revington tank is compatable with the standard sensor? What would be an easy way of checking the sensor operation without removing it from the tank. (Is it possible to remove it without taking the tank out?) I assume putting some resistance across the sensor terminals, but what value?

 

Secondly the Ammeter shows a discharge when ignition is swiched on (Bosch Pump running) but no positive amps when engine running. The ignition warning light goes out and putting a Voltmeter across the battery shows 13.8 volts so the (new) alternator is working?

 

Any ideas, thanks Rich

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A quick way to check the sender is with a wire hook about a foot long. Open the filler cap and look down and to the right hand side of the tank and you will see the sender float and its wire holder,hook your bit of wire under it and lift whilst observing the gauge.(obviously you will need the ignition switched on)

Stuart.

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the Ammeter shows a discharge when ignition is swiched on (Bosch Pump running) but no positive amps when engine running. The ignition warning light goes out and putting a Voltmeter across the battery shows 13.8 volts so the (new) alternator is working?

 

Strange.

So everything is wired through the ammeter? The alternator on the credit side, the main fuse-box on the debit side? No sneaky little off-balance sheet side branches?

 

With no electrical load, you should have a voltage at the fuse box of about 14.5V between the main alternator feed (brown, I think - check!) and earth.

Unfortunately one can't achieve 'no load' in a 6, so with the pump running, 13.8V at this point would indeed indicate that the alternator is doing its stuff.

 

TBH if it's wired right, I don't know why your ammeter is suggesting that all is not well. Unless you have some serious load or a bad short that you're not aware of.

 

My idea, in fact, would be to dodge round that issue by binning the ammeter and fitting a voltmeter. It will tell you all that an ammeter should, but without the risk of the two big fat unfused wires that feed the ammeter. And without the future risk that corrosion or loosening of the ammeter terminals will give you some nasty electrical grief. OK the voltmeter may only be 'correct' on later cars, but..........

 

Be interested to see what some wigglier person can tell you......

 

Ivor

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Rich,

you've kindly offered to help me out with my cam-quest. I'm sure I have a spare working fuel gauge from a Dolomite Sprint in the loft which is identical to the TR6, part no. 159604 which I can give you if you want.

Chris

chris.gosling@ntlworld.com

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Thanks Stuart, doh! why did'nt I think of that <_< At least it's proven that the wiring is functional as when lifting the float arm to it's maximum I get 1/2 reading. So I'm guessing that maybe the gauge is out. I wonder if it's possible to adjustment the gauge to give max deflection at max float hieght?

 

Thanks Rich

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Rich,

 

The voltage for both Fuel and Temperature gauges is maintained by a voltage stabiliser mounted on the back of one of the instruments (speedometer I think!). If your sender works and you've got a good battery, then that could be your problem. If so, then when you get the engine running the temperature gauge will also be "lazy".

 

Bob

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Rich,

 

The voltage for both Fuel and Temperature gauges is maintained by a voltage stabiliser mounted on the back of one of the instruments (speedometer I think!). If your sender works and you've got a good battery, then that could be your problem. If so, then when you get the engine running the temperature gauge will also be "lazy".

 

Bob

 

Thanks Bob, allready thought of that and changed the voltage stabiliser. The temperature gauge works fine so I think it's only the fuel gauge that's got the problem as it only reading 1/2 when the sensor is at max travel. Rich

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There was a previous thread on here about compatability of senders to gauges so it may be worth trying a search.

Stuart.

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