Champ fuel guage-mind of its own.

[Rick W]

The Champs fuel guage seems to have a mind of its own and we are of different opinions as to what is causing it. On tickover and revving up it stays static, as you drive it flips all over the place. One train of thought is suggesting the in tank float is cream crackered, the other is suggesting it is more electrical related. Any experiences?

[Marmite!!]

Voltage stabiliser (if it has one?)

[Willyslancs]

i would say voltage stabilizer too . an old mini i had did this , a new one cured it ,............

[Chrisg]

There's no voltage stabliser. They move around a bit while driving.Mine varies by about 1/4 depending weather up or down hill

[sirhc]

The float has probably absorbed some fuel over the last 50 years. These gauges are never that reliable, the one on my Ferret does what it likes. I never let it go lower than 1/4.

[ArtistsRifles]

The float has probably absorbed some fuel over the last 50 years. These gauges are never that reliable, the one on my Ferret does what it likes. I never let it go lower than 1/4.

 

You'd love my Stalwarts right now then - NOT!!

As soon as the main isolator is turned on the gauge swings over to max deflection no matter whether it's reading fuel level or the button is pressed for engine oil level........... :shake: :shake:

[Guest catweazle (Banned Member)]

Its a strange set up,i spent a long time getting mine right,they do swing about a little.it could drive you mad trying to get it correct.i would suggest you drain the tank

,the drain plug if it is seized will probably crack around the soldered plate if you force it .This will meen taking the tank out to fix it.So use another method.Then add measured amounts of fuel and note your readings on the gauge.It may be theres nothing wrong with it.allthough the sender units are available fairly easy a realiable gauge used is not,new are rare and i have had REME rebuilt dash fail within a month,

so make sure you really need do this or it will drive you bonkers believe me.:nut::nut::nut::trustme:

[Rick W]

Thanks for all that, it doesnt swing by a 1/4 it literally is all over the shop. Guess the least stressful route is to make sure the jerry can/petrol tank is full. I did wonder as it was FFW wether some part of the electrics was playing a part, especially hen under load/driving.

[fv1609]

No voltage regulation is needed as it will work over a wide range of voltages as the system compares ratios of resistance & is independent of voltage.

 

It is Desyn type indicator, which can be viewed as a potentiometer consisting of 3 windings in series like a triangle with 2 wiper arms which are insulated from each other. All connections are wired in parallel to a similar set of 3 windings in delta arrangement in a moving coil indicator. A voltage applied across the wiper arms means that the position of the wiper arms is mimicked in the display meter.

 

The Desyn sensors are identical to those used in aircraft fuel tanks as is the cork float. The wiper arms can lose their spring & the windings can become a bit worn. This is especially true of the windings that correspond to the low end of the scale. The top end of the scale doesn't wear out as the tank is rarely that full.

 

This means there are 5 connections to the sensor, it is not unknown for them to become intermittent & indeed they have to go via a changeover switch to the display gauge which increases the chance of a dodgy connection in the bullet connectors. Failure of a connection to just one winding upsets the whole balance of the system & you can be low on fuel to suddenly find it reading nearly full.

 

I have have a few brand new sensor heads if anyone is really stuck.

[Richard Farrant]

To add to Clive's good comprehensive explanation, I have also seen the 5 wires going to the sender, missplaced, although it should not happen, somebody might have got it wrong, so worth checking. Not all the wires, I might add, but a couple transposed.