Fuel gauge
Fuel gauge
Even when full the fuel gauge only shows half full. Is this likely to be the gauge itself or the sender unit?
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fv1620
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Re: Fuel gauge
Is it a 12v or 24v system?
Does it behave the same way on both tanks?
Does it behave the same way on both tanks?
Clive Elliott
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
Re: Fuel gauge
12 v only one tank, for the moment.
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fv1620
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Re: Fuel gauge
Do you have the sender from the other tank to simulate a full tank with it?
The reason I asked about 12v or 24v is because the fuel reading systems differ.
On your 12v system you will have a 10v voltage stabilizer (which is not a regulator) with a bimetallic strip it constantly switches on & off so that the average voltage equates to 10v. There could be a fault on this stabiliser as well as the sender & gauge being suspect. I think that these voltage stabilisers need to be mounted a certain way up due to the sag in the strip when it heats up. So check that it is positioned correctly & try another if you have one it doesn't depend on the ammeter drawing current to make it function.
This constant switching of the stabiliser does not cause rapid fluctuations in the ammeter because that depends on the heating effect of a bimetallic strip & has a certain slowness to respond that smooths it out.
The switching though is a potent source of RFI (Radio Frequency Interference) which is not welcome in an FFR vehicle. This is why the fuel indication system on a 24v vehicle is different. Despite some colourful diagrams on the internet that show a voltage stabiliser on 24v vehicles this is incorrect, the artist has assumed that somehow the original draughtsman who produced the circuit diagrams just forget to drawn in a stabiliser!
The 24v ammeters have two coils one winding causes the needle to point full & the other to make the needle read empty. Voltage changes have no overall effect as they effect both windings, all that matters is the ratio of the resistance of the sender in relation to the coil winding. So these ammeters have three terminals, people only see two & indeed for simplicity the circuit diagram shows two but the third is the ammeter case.
The reason I asked about 12v or 24v is because the fuel reading systems differ.
On your 12v system you will have a 10v voltage stabilizer (which is not a regulator) with a bimetallic strip it constantly switches on & off so that the average voltage equates to 10v. There could be a fault on this stabiliser as well as the sender & gauge being suspect. I think that these voltage stabilisers need to be mounted a certain way up due to the sag in the strip when it heats up. So check that it is positioned correctly & try another if you have one it doesn't depend on the ammeter drawing current to make it function.
This constant switching of the stabiliser does not cause rapid fluctuations in the ammeter because that depends on the heating effect of a bimetallic strip & has a certain slowness to respond that smooths it out.
The switching though is a potent source of RFI (Radio Frequency Interference) which is not welcome in an FFR vehicle. This is why the fuel indication system on a 24v vehicle is different. Despite some colourful diagrams on the internet that show a voltage stabiliser on 24v vehicles this is incorrect, the artist has assumed that somehow the original draughtsman who produced the circuit diagrams just forget to drawn in a stabiliser!
The 24v ammeters have two coils one winding causes the needle to point full & the other to make the needle read empty. Voltage changes have no overall effect as they effect both windings, all that matters is the ratio of the resistance of the sender in relation to the coil winding. So these ammeters have three terminals, people only see two & indeed for simplicity the circuit diagram shows two but the third is the ammeter case.
Clive Elliott
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
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fv1620
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Re: Fuel gauge
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Clive Elliott
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
Re: Fuel gauge
Hi I'm converting from 24 to 12v on my lightweight restoration I am just going to use 1 tank at the moment but I take it I'll need to change the fuel float and sender right? ![Image]()
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fv1620
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Re: Fuel gauge
Yes, sender & gauge.
Clive Elliott
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.
Collecting military technical publications, researching into military vehicle electrical systems, licensed radio amateur since 1964 using microwave bands for tropospheric scatter.