fixing the electrics on a sprint

[matt of the vivas]

http://www.ebay.co.uk/itm/like/31041849 ... 108&ff19=0

[Mad Mart]

These are available from club stock. They are digital versions.

If you put the VS back on the car. Keep the multimeter set to how you described. With the black probe on the battery -ve or known good ground, touch the red probe to each of the terminals in turn. One will give you battery voltage (12V). The other should be around 10V. Remember the casing of the VS must have a good ground.

[tarynus]

Thank you, so i did that and the right terminal indicates 11.7 v but the left one keeps moving and changing values. Does that mean the vs is faulty?

[Mad Mart]

I may have misled you a bit there. If you have a cheap multimeter it won't be able to measure the outcoming 10V supply from the VS. That's why your values are changing. You see the wire wound around one side of the strip? when you have current flowing from the 12V supply side, that heats up, the metal bends and breaks contact with the other bit so no current is then flowing. No current means the strip cools down and the metal strip bends back again making contact and current flows again. it does this several times per second so a cheap multimeter won't be able to keep up. It works similar to your indicator flasher unit. Only the flasher unit makes and breaks about once a second. If you have a more expensive multimeter with True RMS it will average the reading or a scope would be the tool to get....but I digress.

11.7V is low, should be 12.6V, the same as the battery. Check your battery again and make sure all your connections are clean.

[tarynus]

Thanks Mart,
So do this mean my VS is 100% ok and the problem is located elsewhere? I check the 3 fuel tank wires and one of them shows random values,the other shows nothing and the 3rd(smallest and black is ,i believe ground)

[Jon Tilson]

Your fuel tank sender is a variable resistor connected to a float. As the float rises and sinks it should
change the gauge reading.

The extra terminal is for the low fuel level warning light.

If you earth out the terminal from the gauge you should see the gauge read full.

Be careful if you take the float out of the tank with live wires and a fuel vapour source....

Jonners

[tarynus]

Hi Jon,
The fuel tank is out so no danger there.
When I reconnect the float and move it up or down nothing happens, what should I be looking at?
Is the VS definitly ok or could changing it solve everything? (as I said the right terminal indicates 11.7 v but the left one keeps moving and changing values)

[Richard the old one]

If you are using a digital multimeter to read the output from an old type voltage regulator you will not get a true reading and it will constantly be changing, you need to use an analogue meter, one with a needle, as that will read the true RMS value.

[Jon Tilson]

Sounds like you have the terminals on the float the wrong way round.
Find which one sends the gauge to full when you earth it, then put that on the terminal that changes
on the float - or have I got the wrong end of the stick?

The VS is irrelevent to the float valve and gauge. It will just make it read too high or too low...

Jonners

[elmefrio]

I have "Solid-state" digital voltage stabilizer either on Sprint and Spiftire and after fitting, no more reading problems.

[tarynus]

Ok, so i found the terminal which sent the gauge to full when earthed ( well not full actually, it only went half way up , as the temperature gauge does too). But when i connect it to the float nothing moves. The float was a quite rusty when it took it out of the tank, i sank it in white vinegar for a few days, maybe that didnt do it much good...

[Jon Tilson]

Looks like the potentiometer on your tank sender has gone then.
Can you measure it with your resistance meter? This will tell you for sure. At least the wiring from gauge
to tank looks good. It can sometimes get lost in one of the multiplug connectors under the dash.

New or secondhand senders are available. I may even have one in my collection...

Jonners

[tarynus]

Thanks jon, that would be great let me know if you can find a spare one.
So I have clean all ground wirings I could find but I still get 11,7 v instead of 12,5v on those 2 cables (dark green and white), any idea why?

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[Mad Mart]

It can only be bad ground(s) or dirty connections. Watch this vid from 'Eric the Car Guy' & check for ground & voltage drop.

https://www.youtube.com/watch?v=MhnVZ7ZPunw

[tarynus]

Thanks Mart i'll try some of "ericthecarguy"'s recommandations see how it works out