Valvoman

Fuel gauge does not move and sits at half full...

Is this a fuse or a sending unit?

All other gauges run fine.

scope103

not a fuse (powered through the gauge fuse). Could be the sending unit. Could be the gauge unit (in the combination meter). Since you get 1/2, it is probably not the wiring.

The Toyota fuel gauge uses a '60s era "constant current source," so that the gauge (working as a voltmeter) can consistently measure the resistance of the sender (without wandering around due to changes in the rail voltage). I've never taken one apart, but I understand that the current source is a relay that opens and closes at near to once/second, so that the average current over time flowing through the circuit is constant. In other words, a bunch of parts, which if they don't work right, can leave the gauge at 1/2.

If it was my truck, I'd disconnect the sender from the combination meter, and wire in one my $6 multimeters to measure resistance. Then I'd fill up, and see if the sender changed resistance, consistent with the spec. http://web.archive.org/web/201102052.../6combinat.pdf (measuring resistance this low requires care; you need to assure that your meter connections don't change resistance on their own due to vibration, etc. Don't just tape them together; use a real crimp or some sort of screw clamp to get a consistent connection.)

Valvoman

Scope - you have the skills I don't. However, I do have a multimeter.

wyoming9

iTrader: (1)

More then likely sending unit is toast

Or else the wire going to the gauge is shorted sending a signal that never changes

I have been planning to fix my fuel gauge for 10 years I am so used to it not working now why bother.

Valvoman

I ended up filling it up today. Once I did, the gauge moved all the way over to full. There you go.

Anyway, I calculated my average mileage and it came out to 17.96. Is this possible with this V6 pig? Very little stop and go, no a/c on - heck it's winter in Phoenix!

Terrys87

iTrader: (1)

The 3.0 and 22 in 4 wheel drive trucks really don't do that well in mileage. Just by what you are posting for mileage, I would say you have the 5 speed transmission, the automatic usually gets a little worse then the standard.

One possible and common problem with your fuel gauge is the chemical build up on your float assembly wont let the float rise and fall as it should. I have pulled the float and with a brass tooth brush and some PB Blaster have gotten them to operate like they should.

Another problem I have seen, is the coil in the float is basically a variable resistor that is made up of fine wire about the size of a human hair wound up in a coil. Usually the wiper just rubs thru the wire and breaks the wire. Below is some examples of what I am talking about.



Here is a better view of the wiper that slides on the coil. It had some broken strands so is no good now. A spare that I had.

Valvoman

Yup. It's a manual.

Thanks for the pics. I know what to look for now.