My GTR Dash Fuel Guage is just going crazy it works fine with the amount of fuel in the drop tank but problem is when i drive its always moving left to right trying to balance itself.....is this the Dash or would this be the Fuel Sender Unit???
Fuel Guage going Psycho!
Started by
gooley
, Sep 15 2006 07:16 PM
5 replies to this topic
#1
gooley
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Posted 15 September 2006 - 07:16 PM
#2
Tiny
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Oh My, Don't you post alot
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Posted 15 September 2006 - 07:47 PM
I have no idea about the GTR dashes, but most dashes havea regulator that smooths out these fluctuations.. your guage seems to be showing exactly what the sender is showing it! every slosh on the road!
Often these dampeners burn out giving maximum voltage and stuffing the guage, but i recall hearing about them just dying and not dampening the signal.
Hopefully it's the same for the GTR dashes!
Often these dampeners burn out giving maximum voltage and stuffing the guage, but i recall hearing about them just dying and not dampening the signal.
Hopefully it's the same for the GTR dashes!
#3
_Yella SLuR_
_Yella SLuR_
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Posted 15 September 2006 - 09:34 PM
Get fuel guage that hasn't been scheduled.....
Sorry bad joke. Try work out if it is the guage or the sender first. Could be poor contact on the sender, or earth issue. See if it stops when running a jumper lead from somewhere on the tank to a good earth on the body. If not, start diagnosing the sender for almost broken wire.
Sorry bad joke. Try work out if it is the guage or the sender first. Could be poor contact on the sender, or earth issue. See if it stops when running a jumper lead from somewhere on the tank to a good earth on the body. If not, start diagnosing the sender for almost broken wire.
#4
_UCV80_
_UCV80_
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Posted 15 September 2006 - 09:44 PM
mine goes up and down with the waves 
mines aftermarket though
mines aftermarket though
#5
_finer70_
_finer70_
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Posted 18 September 2006 - 07:11 PM
Try running a dedicated earth wire from the frame of the gauges to a known ground point on the body.
If there is not a sound eatrh gauges, power is forced to track back through instruments making them go wild.
If there is not a sound eatrh gauges, power is forced to track back through instruments making them go wild.
#6
Dangerous
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Posted 19 September 2006 - 10:58 AM
LCs and LJs don't have dash voltage regulators, and their gauges can't be burned out anywhere near as easily as LH/LX ones. LC, LJ and some of the HQ gauges operate on opposing electromagnets - one is a constant magnetism, and the other one is dependent on the sender unit resistance. The needle is balanced between the two electromagnets, according to the relative level of both magnetic fields. When a sender unit goes open circuit, one magnet dies completely, and the gauge hits the limit hard.
LH, LX HJ onwards to mid series Commodores (dunno about the latest ones) use thermal gauges, as not only are they cheaper, but the fact that they use heat to bend the gauge pointer means that they have built in damping, as the bimetallic strip takes a little while to heat up and cool down.
That's why LC/LJ/HQ gauges react quite fast, and later ones react much slower.
LC/LJ tanks tend to be much better earthed than the LH/LX ones, as they're screwed in, unlike the LH/LX ones that are just sandwiched in with two straps.
If the gauge sits steady when the car's not moving, but hits HARD up against the full mark while driving (especially at a certain fuel level), it's usually a sign of the sender unit having a spot on the winding which is open circuit, or which the wiper contact on the float assembly does not touch the winding. Every time the fuel float moves through this position, the gauge needle will violently move immediately to the Full mark, and make an audible sound as it hits the gauge stop.
If it's only the fuel gauge that is acting up, and it's very violent/rapid, I'd suggest it's definitely the sender. If it's the temp and oil gauges as well, it's more likely to be an earth - either dash earth, or the one from the battery neg to the radiator support panel - these were never big enough, even from factory.
LH, LX HJ onwards to mid series Commodores (dunno about the latest ones) use thermal gauges, as not only are they cheaper, but the fact that they use heat to bend the gauge pointer means that they have built in damping, as the bimetallic strip takes a little while to heat up and cool down.
That's why LC/LJ/HQ gauges react quite fast, and later ones react much slower.
LC/LJ tanks tend to be much better earthed than the LH/LX ones, as they're screwed in, unlike the LH/LX ones that are just sandwiched in with two straps.
If the gauge sits steady when the car's not moving, but hits HARD up against the full mark while driving (especially at a certain fuel level), it's usually a sign of the sender unit having a spot on the winding which is open circuit, or which the wiper contact on the float assembly does not touch the winding. Every time the fuel float moves through this position, the gauge needle will violently move immediately to the Full mark, and make an audible sound as it hits the gauge stop.
If it's only the fuel gauge that is acting up, and it's very violent/rapid, I'd suggest it's definitely the sender. If it's the temp and oil gauges as well, it's more likely to be an earth - either dash earth, or the one from the battery neg to the radiator support panel - these were never big enough, even from factory.
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