Gas gauge problem

[GQPorkroll]

Landed myself in a bit of strife the last few weeks. I put $30 gas in my truck and it read 3 lights, then after a day or so it dropped to 2 lights. I didn't pay much attention to my odometer as I don't really go far. One morning I start up to go to work and it won't rev. After 30 mins scratching my head I flick it to petrol and it runs fine. Drive to the servo and put another $30 in and it's good to go

Today, I've just noticed it won't rev on gas again but it's still showing 2 bars on my gauge.

Is there a way to replace the sender? I know gas isn't overly accurate but if I see half a tank I tend not to worry, I always put fuel in before the red light comes on.

I personally think it's a sender problem, more than a gauge problem, however I plan to replace the gauge with one that has the switch inbuilt to make it a little cleaner and neater and so I don't bump the change over switch with my knee every time I get out of the car.

So how do I change a sender in a gas tank?

[GQ TANK]

Before you change the sender check it.

The sendors are 0 - 90ohm depending on the gas level

If you remove your gas gauge, onr of the wires will be going to the back of the truck - this is goes to the sendor.

With the tank empty measure the resistance - fill the tank measure it again. Run the truck for a day or too nad keep checking the gauge, - this test is for the ignbition being off.

The other option is to wire the meter in - One side to the tank wire & ground the other. Set the meter to volts, as the gas level drops - the volts will drop. - while the truck is running.

Yous should see the volts jump around a bit as you go down a byumpy road.

I have been playing with a micro & display and found I have to take a lot of readings over a number of seconds and then determine the average due to the volts jumping.

I belove you cna change the gause with affecting the tank

[GQPorkroll]

Did an ohms test on the tank, came up with 6.8 from memory. The gauge on the tank showed in the red zone.
Did an ohms test at the gauge inside and when the ignition was on, but motor not running, saw similar results and only red light was showing on my gauge.
Start the motor and it goes up to 44.5ohms and sits stable with 2 lights on.
Tested the 12v line and there was no power there. Ran a wire from the battery to the terminal and results were duplicated.
Sprayed all connections with contact cleaner and re earthed the earth with no change.

I have been planning on swapping switches and gauges for some time now, so this will be my next move, if that doesn't cure it, I will replace the in tank sender. The tank sat empty for a while as I fitted a new rear bar and didn't have a hole to mount the filler, so perhaps something has got gummed up. Ill fill it right up this week and see if that frees it up at all.