Fuel Gauge Question
Do a site search. "We" have posted hundreds of posts about this.
The gauge unit may be out of cal
The instrument voltage limiter by any other name may be "off"
The sender especially if it's a "repop" is a large problem
The factory gauge tester (read your service manual) was a switchbox with 3 resistors, to simulate the senders at low/ empty, mid scale/ 1/2 and high/ full. Here is one version. Someone kindly added the resistances to the photo:
...........so you can also do that "backwards." These test boxes were meant to be put from the sender wire to ground, but you can ALSO "let's say" you know you have 1/2 a tank of actual fuel. "Let's say" you know this because you drained it, filled it and measured it, and then ended up with 1/2 that "measured."
This means the sender when unplugged, and measured with an ohmeter, should read somewhere around 20-25 ohms
If it does, and the gauge doesn't read that, then the gauge/ cluster connections/ IVR is some-ting-wong.
Also notice from the tester resistances that THESE GAUGES ARE NOT linear!!! In other words, twice as much sender resistance doesn't change it from MT to 1/2, and twice that much does not result in "full"
Do a site search. "We" have posted hundreds of posts about this.
The gauge unit may be out of cal
The instrument voltage limiter by any other name may be "off"
The sender especially if it's a "repop" is a large problem
The factory gauge tester (read your service manual) was a switchbox with 3 resistors, to simulate the senders at low/ empty, mid scale/ 1/2 and high/ full. Here is one version. Someone kindly added the resistances to the photo:
...........so you can also do that "backwards." These test boxes were meant to be put from the sender wire to ground, but you can ALSO "let's say" you know you have 1/2 a tank of actual fuel. "Let's say" you know this because you drained it, filled it and measured it, and then ended up with 1/2 that "measured."
This means the sender when unplugged, and measured with an ohmeter, should read somewhere around 20-25 ohms
If it does, and the gauge doesn't read that, then the gauge/ cluster connections/ IVR is some-ting-wong.
Also notice from the tester resistances that THESE GAUGES ARE NOT linear!!! In other words, twice as much sender resistance doesn't change it from MT to 1/2, and twice that much does not result in "full"
